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Document And Entity Information - shares	6 Months Ended
Document And Entity Information - shares	Jun. 30, 2017	Aug. 09, 2017
Document Information [Line Items]
Entity Registrant Name	KEMPHARM, INC
Entity Central Index Key	0001434647
Trading Symbol	kmph
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding (in shares)		14,657,430
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Amendment Flag	false

Condensed Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 12,386	$ 16,762
Restricted cash	1,100	1,100
Marketable securities	41,107	51,003
Trade date receivables		5,003
Prepaid expenses and other current assets	771	489
Total current assets	55,364	74,357
Property and equipment, net	2,148	1,970
Long-term investments	11,215	8,200
Other long-term assets	321	360
Total assets	69,048	84,887
Liabilities and stockholders' deficit
Accounts payable and accrued expenses	6,303	6,444
Current portion of capital lease obligation	177	157
Other current liabilities	112	41
Total current liabilities	6,592	6,642
Convertible notes, net	91,950	91,170
Derivative and warrant liability	8,311	4,618
Other long-term liabilities	1,472	1,153
Total liabilities	108,325	103,583
Commitments and contingencies (Note D)
Stockholders’ deficit:
Common stock, $0.0001 par value, 250,000,000 shares authorized, 14,657,430 shares issued and outstanding as of June 30, 2017 (unaudited); 14,646,982 shares issued and outstanding as of December 31, 2016	1	1
Additional paid-in capital	104,901	102,643
Preferred stock, $0.0001 par value, 10,000,000 shares authorized, no shares issued or outstanding as of June 30, 2017 (unaudited) and December 31, 2016	0	0
Accumulated deficit	(144,179)	(121,340)
Total stockholders' deficit	(39,277)	(18,696)
Total liabilities and stockholders' deficit	$ 69,048	$ 84,887

Condensed Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	14,657,430	14,646,982
Common stock, shares outstanding (in shares)	14,657,430	14,646,982
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0

Unaudited Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue
Operating expenses:
Research and development	4,650	4,988	8,764	8,222
General and administrative	3,574	4,287	6,840	8,023
Total operating expenses	8,224	9,275	15,604	16,245
Loss from operations	(8,224)	(9,275)	(15,604)	(16,245)
Other (expense) income:
Loss on extinguishment of debt				(4,740)
Interest expense related to amortization of debt issuance costs and discount	(390)	(393)	(780)	(835)
Interest expense on principal	(1,443)	(1,475)	(2,884)	(2,625)
Fair value adjustment	3,523	20,763	(3,693)	31,041
Interest and other income, net	13	144	114	246
Total other (expense) income	1,703	19,039	(7,243)	23,087
(Loss) income before income taxes	(6,521)	9,764	(22,847)	6,842
Income tax benefit (expense)	4	4	8	(8)
Net (loss) income	$ (6,517)	$ 9,768	$ (22,839)	$ 6,834
Net (loss) income per share:
Basic (in dollars per share)	$ (0.44)	$ 0.59	$ (1.56)	$ 0.41
Diluted (in dollars per share)	$ (0.44)	$ (0.58)	$ (1.56)	$ (1.36)
Weighted average number of shares of common stock outstanding:
Basic (in shares)	14,649,586	14,597,449	14,648,291	14,546,576
Diluted (in shares)	14,649,586	15,435,322	14,648,291	15,583,390

Unaudited Condensed Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net (loss) income	$ (22,839)	$ 6,834
Adjustments to reconcile net (loss) income to net cash used in operating activities:
Loss on extinguishment of debt		4,740
Write-off of deferred offering costs		445
Stock-based compensation expense	2,254	2,279
Non-cash interest expense	2,220	2,443
Amortization of debt issuance costs and debt discount	780	835
Depreciation and amortization expense	164	55
Fair value adjustment	3,693	(31,041)
Loss on sublease	102
Change in assets and liabilities:
Prepaid expenses and other assets	(151)	1,932
Accounts payable and accrued expenses	(2,318)	(693)
Other liabilities	101	32
Net cash used in operating activities	(15,994)	(12,139)
Cash flows from investing activities:
Purchases of property and equipment	(143)	(219)
Purchases of marketable securities and long-term investments	(20,922)	(65,627)
Maturities of marketable securities	32,806	10,645
Net cash provided by (used in) investing activities	11,741	(55,201)
Cash flows from financing activities:
Proceeds from issuance of debt, net of discounts and commissions		82,800
Repayment of term notes and related accrued interest		(18,621)
Payment of deferred offering costs	(50)
Payment of debt and stock issuance costs		(673)
Repayment of obligations under capital lease	(77)	(15)
Proceeds from exercise of warrants	4	141
Net cash (used in) provided by financing activities	(123)	63,632
Net decrease in cash and cash equivalents	(4,376)	(3,708)
Cash and equivalents, beginning of period	17,862	32,318
Cash and equivalents, end of period	13,486	28,610
Supplemental cash flow information:
Cash paid for interest	2,857	182
Transfer of warrants to equity upon exercise		755
Fixed assets included in accounts payable and accrued expenses	7	50
Deferred offering costs included in accounts payable and accrued expenses	60
Fixed assets financed under a lease agreement	$ 284	$ 548

Note A - Description of Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2017
Notes to Financial Statements
Business Description and Basis of Presentation [Text Block]	KEMPHARM, INC. NOTES TO UNAUDITED CONDENSED FINANCIAL STATEMENTS A. Description of Business and Basis of Presentation Organization KemPharm, Inc. (the “ Company”) is a clinical-stage specialty pharmaceutical company engaged in the discovery and development of proprietary prodrugs. Through the use of its Ligand Activated Therapy (“LAT ™ ”) platform technology, the Company is able to initiate and pursue the development of improved versions of widely prescribed, approved drugs. The Company was formed and incorporated in Iowa on October 30, 2006 and reorganized in Delaware on May 30, 2014. The Company has experienced recurrin g losses from operations and negative operating cash flows due to its ongoing research and development of its potential product candidates. The Company also has an accumulated deficit at June 30, 2017. Various internal and external factors will affect whether and when the candidates become approved drugs and how significant their market share will be. The length of time and cost of developing and commercializing these candidates and/or failure of them at any stage of the drug approval process will materially affect the Company’s financial condition and future operations. The accompanying unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for inter im financial information and with the instructions to Form 10 -Q and Rule 8 - 03 of Regulation S- X. Accordingly, they do not include all of the information and related notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included in the accompanying financial statements. Operating results for the three and six months ended June 30, 2017 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2017. This interim information should be read in conjunction with the audited financial statements included in the Company ’s Annual Report on Form 10 -K for the fiscal year ended December 31, 2016, filed with the Securities and Exchange Commission (“SEC”) on March 10, 2017. Initial Public Offering and Reverse Stock Split In 2015, the Company completed an initial public offering ("IPO") of its common stock. Prior to the comm encement of the IPO, the Company effected a 1 -for- 7.5 reverse stock split of its issued common stock. Upon completion of the IPO, all outstanding shares of the Company's redeemable convertible preferred stock were converted or reclassified into shares of common stock and all outstanding warrants to acquire shares of the Company's redeemable convertible preferred stock became warrants to acquire the Company's common stock. In connection with the IPO, the Company amended and restated its Amended and Restated Certificate of Incorporation to change the authorized capital stock to 250,000,000 shares designated as common stock, and 10,000,000 shares designated as preferred stock, each with a par value of $0.0001 per share. Reclassifications During the second quarter of 2017, the Company early adopted Accounting Standards Update (“ASU”) 2016 - 18, Statements of Cash Flows (Topic 320 ) – Restricted Cash ("ASU 2016 - 18" ), which addresses the treatment of restricted cash and restricted cash equivalents in the statement of cash flows . The adoption of ASU 2016 - 18 reduced the Company’s net cash used in investing activities and net decrease in cash and cash equivalents on the condensed statements of cash flows by $1.1 million for the six months ended June 30, 2016, as compared to the net cash used in investing activities and net decrease in cash and cash equivalents on the condensed statements of cash flows if the Company had not early adopted ASU 2016 - 18. This reclassification had no effect on the condensed balance sheets or statements of operations. Entry into ATM Agreement On October 3, 2016, the Company entered into a Common Stock Sales Agreement (the "ATM Agreement") with Cowen and Company, LLC ("Cowen") under which the Company may offer and sell, from time to time, in its sole discretion, shares of common stock having an aggregate offering price of up to $50,000,000 through Cowen as the Company's sales agent. The Company's registration statement on Form S- 3 contemplated under the ATM Agreement was declared effective by the SEC on October 17, 2016. The registration statement on Form S- 3 included a prospectus covering the offering up to $20,000,000 of shares of common stock in accordance with the ATM Agreement. Cowen may sell common stock under the ATM Agreement by any method permitted by law deemed to be an "at the market offering" as defined in Rule 415 of the Securities Act, including without limitation sales made by means of ordinary brokers' transactions on The NASDAQ Global Market or otherwise at market prices prevailing at the time of sale, in block transactions, or as otherwise directed by the Company. Cowen will use commercially reasonable efforts to sell the common stock from time to time, based upon instructions from the Company (including any price, time or size limits or other customary parameters or conditions the Company may impose). The Company will pay Cowen a commission of up to 3.0% of the gross sales proceeds of any common stock sold through Cowen under the ATM Agreement, and has provided Cowen with customary indemnification rights. The Company is not obliga ted to make any sales of common stock under the ATM Agreement. The offering of shares of common stock pursuant to the ATM Agreement will terminate upon the earlier of (i) the sale of all common stock subject to the ATM Agreement, or (ii) termination of the ATM Agreement in accordance with its terms. As of June 30, 2017, the Company has made no sales of its common stock pursuant to the terms of the ATM Agreement and had deferred offering costs related to the offering contemplated by the ATM Agreement recorded within prepaid and other current assets and other long-term assets in the amount of $0.2 million.

Note B - Summary of Significant Accounting Policies	6 Months Ended
Note B - Summary of Significant Accounting Policies	Jun. 30, 2017
Notes to Financial Statements
Significant Accounting Policies [Text Block]	B. Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those rel ated to the useful lives of property and equipment, and assumptions used for purposes of determining stock-based compensation, income taxes, and the fair value of the derivative and warrant liability, among others. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable, the results of which form the basis for making judgments about the carrying value of assets and liabilities. Application of New or Revised Accounting Standards —Adopted From time to time, the Financial Accounting Standards Board (the “ FASB”) or other standard-setting bodies issue accounting standards that are adopted by the Company as of the specified effective date. On April 5, 2012, President Obama signed the Jump-Sta rt Our Business Startups Act (the “JOBS Act”) into law. The JOBS Act contains provisions that, among other things, reduce certain reporting requirements for an emerging growth company. As an emerging growth company, the Company could have elected to adopt new or revised accounting standards when they become effective for non-public companies, which typically is later than public companies must adopt the standards. The Company elected not to take advantage of the extended transition period afforded by the JOBS Act and, as a result, will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for non-emerging growth companies. In November 2015, the FASB issued ASU 2 015 - 17, Income Taxes: Balance Sheet Classification of Deferred Taxes (Topic 740 ) ("ASU 2015 - 17" ), which requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. This update applies to all entities that present a classified statement of financial position. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The adoption of ASU 2015 - 17 did not have a material impact on Company's financial statements and disclosures as the Company maintains a full valuation allowance. In March 2016, the FASB issued ASU 2016 - 06, Derivatives and Hedging (Topic 815 ), Contingent Put and Call Options in Debt Instruments ("ASU 2016 - 06" ), which clarifies the requirements for assessing whether contingent call and put options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. ASU 2016 - 06 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years, with early adoption permitted. The adoption of ASU 2016 - 06 did not have a material impact on Company's financial statements and disclosures. In March 2016, the FASB issued ASU 2016 - 09, Compensation–Stock Compensation (Topic 718 ), Improvements to Employee Share-Based Payment Accounting ("ASU 2016 - 09" ), which simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016 - 09 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years, with early adoption permitted. The adoption of ASU 2016 - 09 did not have a material impact on Company's financial statements and disclosures. In November 2016, the FASB issued ASU 2016 - 18, which applies to all entities that have restricted cash or restricted cash equivalents and are required to present a statement of cash flows. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company early adopted ASU 2016 - 18 in the current quarter. Refer to Note A for discussion regarding the impact the adoption of ASU 2016 - 18 had on the Company's financial statements and disclosures. Application of New or Revised Accounting Standards —Not Yet Adopted In May 2014, the FASB issued guidance codified in Accounting Standard Codification ("ASC") Topic 606, Revenue Recognition—Revenue from Contracts with Customers ("ASC 606" ), which amends the guidance in former ASC 605, Revenue Recognition , and becomes effective beginning January 1, 2018. The Company does not currently expect this standard to have a material effect on its financial statements upon adoption since the Company is not generating revenue at this time. In January 2016, the FASB issued ASU 2016 - 01 , Financial Instruments Overall – Recognition and Measurement of Financial Assets and Liabilities (Topic 825 - 10 ) (“ASU 2016 - 01” ), which provides several updates related to Topic 825 - 10. This update applies to all entities that hold financial assets or owe financial liabilities. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2016 - 01 on its financial statements and disclosures. In February 2016, the FASB issued ASU 2016 - 02, Leases (Topic 842 ) (“ASU 2016 - 02” ), which requires lessees to recognize assets and liabilities for operating leases with lease terms greater than twelve months in the balance sheet. The update also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. ASU 2016 - 02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the adoption of ASU 2016 - 02 on its financial statements and disclosures. In August 2016, the FASB issued ASU 2016 - 15, Statement of Cash Flows – Classification of Certain Cash Receipts and Cash Payments (Topic 230 ) (“ASU 2016 - 15” ), which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. This update applies to all entities that are required to present a statement of cash flows under Topic 230. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2016 - 15 on its financial statements and disclosures. In May 2017, the FASB issued ASU 2017 - 09, Compensation – Stock Compensation (Topic 718 ) – Scope of Modification Accounting ("ASU 2017 - 09" ), which provides guidance about which changes to the terms or conditions of a stock-based payment award require an entity to apply modification accounting in Topic 718. This update applies to any entity that changes the terms or conditions of a stock-based payment award. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2017 - 09 on its financial statements and disclosures. In July 2017, the FASB issued ASU 2017 - 11, Earnings Per Share (Topic 260 ), Distinguishing Liabilities from Equity (Topic 480 ), Derivatives and Hedging (Topic 815 ) – I. Accounting for Certain Financial Instruments with Down Round Features and II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception ("ASU 2017 - 11" ), which addresses the complexity of accounting for certain financial instruments with down round features and addresses the difficulty of navigating Topic 480 because of the existence of extensive pending content in the ASC as a result of the indefinite deferral of accounting requirements about mandatorily redeemable financial instruments of certain nonpublic entities and certain mandatorily redeemable noncontrolling interests . This update applies to all entities that issue financial instruments that include down round features and entities that present earnings per share in accordance with Topic 260. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2017 - 11 on its financial statements and disclosures.

Note C - Debt Obligations	6 Months Ended
Note C - Debt Obligations	Jun. 30, 2017
Notes to Financial Statements
Debt Disclosure [Text Block]	C. Debt Obligations Deerfield Facility Agreement On June 2, 2014, the Company entered into a $60 million facility agreement (the “Deerfield Facility Agreement”) with Deerfield Private Design Fund III, LP (“Deerfield”). The first payment to the Company under the terms of the Deerfield Facility Agreement consisted of a term loan of $15 million (the “Term Notes”) and a senior secured loan of $10 million (the “Deerfield Convertible Notes”). As of June 30, 2016, Deerfield is no longer obligated to provide the Company any additional disbursements under the Deerfield Facility Agreement. All loans issued under the Deerfield Facility Agreement bear interest at 9.75% per annum. Deerfield may convert any portion of the outstanding principal and any accrued but unpaid interest on the Deerfield Convertible Notes into shares of the Company’s common stock at an initial conversion price of $5.85 per share (the "Deerfield Note Put Option"). The Company also issued to Deerfield a warrant to purchase 14,423,076 shares of Series D redeemable convertible preferred stock (“Series D Preferred”) at an exercise price of $0.78 per share, which is exercisable until June 2, 2024 (the “Deerfield Warrant”). Upon completion of the IPO, the Deerfield Warrant automatically converted into a warrant to purchase 1,923,077 shares of the Company’s common stock at an exercise price of $5.85 per share. This warrant qualifies as a participating security under ASC Topic 260, Earnings per Share, and is treated as such in the earnings per share calculation (Note I). If a Major Transaction occurs, as defined below, Deerfield may require the Company to redeem the Deerfield Warrant for a cash amount equal to the Black-Scholes value of the portion of the Deerfield Warrant to be redeemed (the “Warrant Put Option”). A Major Transaction is (i) a consolidation, merger, exchange of shares, recapitalization, reorganization, business combination or other similar event; (ii) the sale or transfer in one transaction or a series of related transactions of all or substantially all of the assets of the Company; (iii) a third -party purchase, tender or exchange offer made to the holders of outstanding shares, such that following such purchase, tender or exchange offer a change of control has occurred; (iv) the liquidation, bankruptcy, insolvency, dissolution or winding-up affecting the Company; (v) the shares of the Company’s common stock cease to be listed on any eligible market; and (vi) at any time, the shares of the Company’s common stock cease to be registered under Section 12 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). In addition, the Company issued to Deerfield 1,923,077 shares of Series D Preferred as consideration for the loans provide d to the Company under the Deerfield Facility Agreement. Upon completion of the IPO, these shares automatically reclassified into 256,410 shares of the Company’s common stock. The Company recorded the fair value of the shares of Series D Preferred of $1.5 million, to debt issuance costs on the date of issuance. The Company recorded the fair value of the Deerfield Warrant and the embedded Warrant Put Option to debt discount on the date of issuance. The debt issuance costs and debt discount are amortized over the term of the related debt and the expense is recorded as interest expense in the condensed statements of operations. Pursuant to the Deerfield Facility Agreement, the Company may not enter into specified transactions, including a debt financing in the aggregate value of $750,000 or more, a merger, an asset sale or any other change of control transaction or any joint venture, partnership or other profit sharing arrangement, without the prior approval of Deerfield. Additionally, if the Company were to enter into a major transaction, including a merger, consolidation, sale of substantially all its assets or other change of control transaction, Deerfield would have the ability to demand that prior to consummation of such transaction the Company repay all outstanding principal and accrued interest of any notes issued under the Deerfield Facility Agreement. Under each warrant issued pursuant to the Deerfield Facility Agreement, Deerfield has the right to demand that the Company redeem the warrant for a cash amount equal to the Black-Scholes value of a portion of the warrant upon the occurrence of specified events, including a merger, an asset sale or any other change of control transaction. The Company must repay one - third of the outstanding principal amount of all debt issued under the Deerfield Facility Agreement on the fourth and fifth anniversaries of the Deerfield Facility Agreement. The Company is then also obligated to repay the balance of the outstanding principal amount on February 14, 2020. The Company prepaid all outstanding interest and principal on the Term Notes in February 2016. Interest accrued on outstanding debt under the Deerfield Facility Agreement is due quarterly in arrears. Upon notice to Deerfield, the Company had the option to c hoose to have one or more of the first eight of such scheduled interest payments added to the outstanding principal amount of the debt issued under the Deerfield Facility Agreement, provided that all such interest was due on July 1, 2016. The Company elected this option on all eight of the scheduled interest payments through June 30, 2016. The accrued interest added to outstanding principal was paid to Deerfield on July 1, 2016. Second Amendment to Senior Secured Convertible Note and Warrant On January 6, 2016, the Company entered into a Second Amendment (the “Second Amendment”) to the Deerfield Convertible Notes and Deerfield Warrant, by and between the Company and Deerfield. The Second Amendment, among other things, clarified the calculation of an anti-dilution adjustment of the conversion price and exercise price of the Deerfield Convertible Notes and Deerfield Warrant, respectively, if the Company effects a firm commitment underwritten public offering of its securities. Except as modified by the Second Amendment, the Third Amendment (as described below) and the Fourth Amendment (as described below), all terms and conditions of the Deerfield Convertible Notes and Deerfield Warrant remain in full force and effect. Issuance of 202 1 Notes and Third Amendment to Senior Secured Convertible Note and Warrant On February 9, 2016, the Company issued $86.3 million aggregate principal amount of its 5.50% Senior Convertible Notes due 2021 (the “ 2021 Notes”) to Cowen and RBC Capital Markets, LLC., as representatives of the several initial purchasers (the “Initial Purchasers”), who subsequently resold the 2021 Notes to qualified institutional buyers (the “Note Offering”) in reliance on the exemption from registration provided by Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). The net proceeds from the Note Offering were approximately $82.8 million, after deducting the Initial Purchasers ’ discount and estimated offering expenses. Concurrent with the Note Offering, the Company used approximately $18.6 million of the net proceeds from the Note Offering to repay in full the Term Notes, plus all accrued but unpaid interest, a make-whole interest payment and a prepayment premium on the Term Notes. This principal, accrued but unpaid interest, make-whole interest payment and prepayment premium on the Term Notes is reflected as a cash outflow from financing activity in the condensed statement of cash flows. The 2021 Notes were issued pursuant to an Indenture, dated as of February 9, 2016 (the “Indenture”), between the Company and U.S. Bank National Association, as trustee. Interest on the 2021 Notes is payable semi-annually in cash in arrears on February 1 and August 1 of each year, beginning on August 1, 2016, at a rate of 5.50% per year. The 2021 Notes mature on February 1, 2021 unless earlier converted or repurchased. The 2021 Notes are not redeemable prior to the maturity date, and no sinking fund is provided for the 2021 Notes. The 2021 Notes are convertible at a n initial conversion rate of 58.4454 shares of the Company’s common stock per $1,000 principal amount of the 2021 Notes, subject to adjustment under the Indenture, which is equal to an initial conversion price of approximately $17.11 per share of common stock. Upon conversion, the 2021 Notes will be settled in shares of the Company’s common stock, together with a cash payment in lieu of delivering any fractional share. The conversion rate will be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, the Company will increase the conversion rate for a holder who elects to convert its 2021 Notes in connection with such a corporate event in certain circumstances. If the Company undergoes a “ fundamental change” (as defined in the Indenture), holders may require that the Company repurchase for cash all or any portion of their 2021 Notes at a fundamental change repurchase price equal to 100% of the principal amount of the 2021 Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, holders who convert their 2021 Notes on or after the date that is one year after the last date of original issuance of the 2021 Notes may also be entitled to receive, under certain circumstances, an interest make-whole payment payable in shares of the Company’s common stock. The Company is bifurcating the fundamental change and make-whole interest payment provisions as embedded derivatives and marking them to fair value each reporting period (Note H). The Indenture includes customary terms and covenants, including certain events of default after which the 2021 Notes may be due and pay able immediately. In connection with the Note Offering, on February 3, 2016, the Company entered into a Third Amendment (the “ Third Amendment”) to the Deerfield Facility Agreement, Deerfield Convertible Notes and Deerfield Warrant with Deerfield. The Third Amendment, among other things, eliminated the Company’s ability to require Deerfield to convert the Deerfield Convertible Notes into Company common stock. In addition, pursuant to the Third Amendment, Deerfield consented to the prepayment of the Term Notes and the issuance of the 2021 Notes. Except as modified by the Third Amendment and the Fourth Amendment (as described below), all terms and conditions of the Deerfield Facility Agreement remain in full force and effect. Fourth Amendment to Deerfield Convertible Notes and Deerfield Warrant In connection with entering into the ATM Agreement, on October 3, 2016, the Company entered into a Fourth Amendment (the "Fourth Amendment") to the Deerfield Convertible Note and Deerfield Warrant with Deerfield. The Fourth Amendment, among other things, clarifies the calculation of an anti-dilution adjustment of the conversion price and exercise price of the Deerfield Convertible Note and Deerfield Warrant, respectively, if the Company effects an "at the market offering" as defined in Rule 415 of the Securities Act of its common stock. Line of Credit During the second quarter of 2016, the Company opened a line of credit with a total borrowing capacity of $1.1 million with City National Bank of Florida (the "Line of Credit Agreement") to support several irrevocable letters of credit issued by the bank on behalf of the Company. As of June 30, 2017, the Company had unused letters of credit totaling $0.4 million. The line of credit has a maturity date of January 31, 2018. As of June 30, 2017, the Company had no outstanding balance under the line of credit. The Line of Credit Agreement is collateralized by a restricted money market account, equal to the total amount of the borrowing capacity under the line of credit, held by the same bank institution. The money market account is reported as restricted cash on the condensed balance sheet. The line of credit contains no financial covenants. Borrowings under the Line of Credit Agreement carry interest at a rate equal to the 1 -month London Interbank Offered Rate, or LIBOR, plus 2.00% per annum. The interest rate is updated at the beginning of each month for rate changes that occurred during the previous month. The interest rate under the Line of Credit Agreement was 3.06% as of June 30, 2017.

Note D - Commitments and Contingencies	6 Months Ended
Note D - Commitments and Contingencies	Jun. 30, 2017
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	D. Commitments and Contingencies From time to time, the Company is involved in various legal proceedings arising in the normal course of business. For some matters, a liabilit y is not probable or the amount cannot be reasonably estimated and, therefore, an accrual has not been made. However, for such matters when it is probable that the Company has incurred a liability and can reasonably estimate the amount, the Company accrues and discloses such estimates. As of June 30, 2017 and December 31, 2016, no accruals have been made related to commitments and contingencies. In 2014, a former financial advisor of the Company filed a request with the Iowa District Court to declare vali d a purported right of first refusal to serve as the Company's exclusive financial advisor for specified strategic transactions and to receive fees for the specified strategic transactions irrespective of whether any such specified transaction occurred during or after the term of the financial advisor's service agreement. This filing by the former financial advisor was made in response to an action initiated by the Company in 2013 seeking a declaratory judgement finding that such purported right was invalid and unenforceable. Two former members of the Company's board of directors (the "Board") joined the lawsuit as intervenors based on the former financial advisor's purported assignment of its rights, or a portion thereof, under the agreement to the intervenors. In September 2015, the court granted summary judgement in favor of the Company with respect to the Company's declaratory judgement action and the former financial advisor's counterclaims and the Company separately entered into settlement agreements with each of the intervenors. The settlements reached with the intervenors did not differ from the accrual previously recorded by the Company by a material amount. The former financial advisor subsequently filed a notice of appeal of the court's ruling with the Supreme Court of Iowa. On January 6, 2016, the Company entered into a Settlement Agreement and Mutual Release (the "Settlement Agreement") with the former financial advisor and Donald DeWaay, Jr. pursuant to which, among other things, the former financial advisor agreed, in exchange for the consideration described therein, to dismiss with prejudice its pending appeal. The former financial advisor's appeal was subsequently dismissed by the Supreme Court of Iowa on January 7, 2016. The settlement amount was commensurate with the contingency recorded in the books and records of the Company. The consideration in the settlement agreement did not differ from the accrual previously recorded by the Company by a material amount. In December 2016, a class action suit was filed against the Company in the Iowa District Court in Johnson County by a stockholder alleging that the Company, certain of its senior executives and directors who signed the registration statement in connection with its initial public offering, and each of the investment banks that acted as underwriters for the offering negligently, issued untrue statements of material facts and omitted to state material facts required to be stated in the registration statement and incorporated offering materials that the Company filed with the SEC in support of the offering. The plaintiff does not quantify any alleged damages in his complaint but, in addition to attorneys' fees and costs, the plaintiff seeks to recover damages and obtain other relief on behalf of himself and all other persons who purchased the Company's common stock pursuant or traceable to the offering and the registration statement and who were allegedly damaged thereby. In January 2017, the class action suit was removed to the U.S. District Court for the Southern District of Iowa. The plaintiff subsequently filed a motion to remand the case to the Iowa District Court, and that motion was granted. The suit is still in a preliminary stage and has not yet been set for trial. Accordingly, the Company is unable to predict the timing or outcome of this litigation as of the date of this report. North Carolina Sublease During the second quarter of 2017, the Company subleased its office space in North Carolina under a non-cancelable operating lease to a third -party tenant. The sublease term with the third -party runs concurrent with the lease term the Company has with the landlord.

Note E - Preferred Stock and Warrants	6 Months Ended
Note E - Preferred Stock and Warrants	Jun. 30, 2017
Notes to Financial Statements
Preferred Stock [Text Block]	E. Preferred Stock and Warrants Authorized, Issued, and Outstanding Preferred Stock As of June 30, 2017, the Company had 10,000,000 shares of authorized and undesignated preferred stock, and did not have any preferred stock outstanding. Warrants During 2013, the Company issued $3.8 million of convertible notes and the warrants (the “ 2013 Warrants”) to purchase 1,079,453 shares of equity securities in a future financing meeting specified criteria (a “Qualified Financing”). The 2013 Warrants allow the holders to purchase shares of the same class and series of equity securities issued in the Qualified Financing for an exercise price equal to the per share price paid by the purchasers of such equity securities in the Qualified Financing. When the Company entered into the Deerfield Facility Agreement, the 2013 Warrants became warrants to purchase 1,079,453 shares of Series D preferred stock. Upon completion of the IPO, the 2013 Warrants automatically converted into warrants to purchase 143,466 shares of the Company’s common stock at an exercise price of $5.85 per share. The 2013 Warrants, if unexercised, expire on the earlier of June 2, 2019, or upon a liquidation event. On June 2, 2014, pursuant to the terms of the Deerfield Facility Agreement, the Company issued the Deerfield Warrant to purchase 14,423,076 shares of Series D preferred stock (Note C). The Company recorded the fair value of the Deerfield Warrant as a debt discount and a warrant liability. The Deerfield Warrant, if unexercised, expires on the earlier of June 2, 2024, or upon a liquidation event. Upon completion of the IPO, the Deerfield Warrant automatically converted into a warrant to purchase 1,923,077 shares of the Company’s common stock at an exercise price of $5.85 per share. The Company is amortizing the debt discount to interest expense over the term of the Deerfield Convertible Notes. The Company determined that the 2013 Warrants and Deerfield Warrant should be recorded as a liability and stated at fair value at each reporting period upon inception. As stated above, upon completion of the IPO, the 2013 Warrants and the Deerfield Warrant automatically converted into warrants to purchase the Company’s common stock. The Company marked the 2013 Warrants to fair value and reclassified them to equity upon closing of the IPO. The Deerfield Warrant remains classified as a liability and is recorded at fair value at each reporting period since it can be settled in cash. Changes to the fair value of the warrant liability are recorded through the condensed statements of operations as a fair value adjustment (Note H).

Note F - Common Stock and Warrants

6 Months Ended

Jun. 30, 2017

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

Common Stock and Warrants

Authorized,

Issued, and Outstanding Common Shares

April 2015,

the Company amended and restated

its Certificate of Incorporation to increase the number of its authorized shares of common stock to

250,000,000

shares. Of the authorized shares,

14,657,430

and

14,646,982

shares of common stock were issued and outstanding at

June 30, 2017

and

December

31,

2016,

respectively.

June 30, 2017

and

December 31, 2016,

the Company had reserved authorized shares of common stock for future issuance as follows:

	June 3 0 , 2017		December 31, 2016
Conversion of Deerfield Convertible Notes		1,750,954		1,751,296
Conversion of 2021 Notes		5,040,914		5,040,914
Outstanding awards under equity incentive plans		2,873,344		1,990,260
Outstanding common stock warrants		2,027,763		2,087,477
Possible future issuances under equity incentive plans		928,800		1,244,671
Total common shares reserved for future issuance		12,621,775		12,114,618

Common Stock Activity

The following table summarizes common stock activity for the

six

months ended

June 30, 2017:

	Shares of Common Stock
Balance at December 31, 2016		14,646,982
Common stock warrants exercised		698
Common stock options exercised		9,750
Balance at June 30, 2017		14,657,430

The Company calculates the fair value of common stock warrants using a Monte Carlo simulation.

There were warrants exercised for an aggregate of

698

and

141,095

shares of common stock during the

six

months ended

June 30, 2017

and

2016,

respectively. From

2008

through

2012,

the Company issued warrants to purchase

595,920

shares of common stock in its private placement offerings of Series A redeemable convertible preferred stock, Series B redeemable convertible preferred stock and Series C redeemable convertible preferred stock (the “Underwriter Warrants”) and for leasing laboratory space. The Company accounted for the Underwriter Warrants as a derivative liability, which is adjusted to fair value at each reporting period, with the change in fair value recorded within other (expense) income in the condensed statements of operations.

Note G - Stock-based Compensation

6 Months Ended

Jun. 30, 2017

Notes to Financial Statements

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

Stock-Based Compensation

The Company maintains a stock-based compensation plan (the “

Incentive Stock Plan”) that governs stock awards made to employees and directors prior to completion of the IPO.

November 2014,

the Board, and in

April 2015,

the Company

’s stockholders, approved the Company’s

2014

Equity Incentive Plan (the

“2014

Plan”), which became effective in

April 2015.

The

2014

Plan provides for the grant of stock options, other forms of equity compensation, and performance cash awards. The maximum number of shares of common stock that

may

be issued under the

2014

Plan is

3,432,183

as of

June 30, 2017.

The number of shares of common stock reserved for issuance under the

2014

Plan will automatically increase on

January 1

of each year, beginning on

January 1, 2016,

and ending on and including

January 1, 2024,

of the total number of shares of the Company’s capital stock outstanding on

December 31

of the preceding calendar year, or a lesser number of shares determined, by the Board. Pursuant to the terms of the

2014

Plan, on

January 1, 2017,

the common stock reserved for issuance under the

2014

Plan automatically increased by

585,879

shares.

During the

three

and

six

months ended

June 30, 2017

and

2016,

stock options were exercised for a total of

9,250

and

14,933

shares of common stock, respectively.

Stock-based compensation expense recorded under the Incentive Stock Plan

and the

2014

Plan is included in the following line items in the accompanying condensed statements of operations (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Research and development	$	340	$	268	$	631	$	455
General and administrative		825		989		1,623		1,824
Total		1,165	$	1,257		2,254	$	2,279

There was

stock-based compensation expense related to performance-based awards recognized during the

three

six

months ended

June 30, 2017.

There was

stock-based compensation expense related to performance-based incentive awards recognized during the

three

months ended

June 30, 2016

. During the

six

months ended

June 30, 2016,

the Company recognized

$29,000

of stock-based compensation expense related to performance-based awards included in research and development expenses in connection with the vesting of stock options exercisable for an aggregate of

13,333

shares of common stock as a result of the acceptance of the new drug application for Apadaz

™

, the Company's product candidate which consists of

KP201,

its prodrug of hydrocodone and acetaminophen, for priority review in

February 2016.

Note H - Fair Value of Financial Instruments

6 Months Ended

Jun. 30, 2017

Notes to Financial Statements

Fair Value Disclosures [Text Block]

Fair Value of Financial Instruments

The accounting standard for fair value measurements provides a framework for measuring fair value and requires disclosures regarding fair value measurements. Fair value i

s defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, based on the Company’s principal or, in absence of a principal, most advantageous market for the specific asset or liability.

The Company uses a

three

-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a

non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires the Company to use observable inputs when available, and to minimize the use of unobservable inputs, when determining fair value. The

three

tiers are defined as follows:

●

Level

—Observable inputs that reflect quoted market prices (unadjusted) for identical assets or liabilities in active markets;

●

Level

—Observable inputs other than quoted prices in active markets that are observable either directly or indirectly in the marketplace for identical or similar assets and liabilities; and

●

Level

—Unobservable inputs that are supported by little or

market data, which require the Company to develop its own assumptions.

The carrying amounts of c

ertain financial instruments, including cash and cash equivalents, restricted cash and accounts payable, approximate their respective fair values due to the short-term nature of such instruments.

The fair value of the Deerfield Convertible Notes was

$11.0

million and

$10.2

million, respectively, at

June 30, 2017

and

December 31, 2016.

The fair value of the

2021

Notes was

$50.0

million and

$46.3

million, respectively, at

June 30, 2017

and

December 31, 2016.

Both the Deerfield Convertible Notes and the

2021

Notes fall within Level

of the fair value hierarchy as their value is based on the credit worthiness of the Company, which is an unobservable input. The Company used a Tsiveriotis-Fernandes model to value the Deerfield Convertible Notes and

2021

Notes at

June 30, 2017

and

December 31, 2016.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The Company evaluates its financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate

level in which to classify them for each reporting period. This determination requires significant judgements to be made. The following table summarizes the conclusions reached regarding fair value measurements as of

June 30, 2017

and

December

31,

2016

(in thousands):

	Balance at June 30 , 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Deerfield Warrant liability		5,212		—		—		5,212
Embedded Warrant Put Option		461		—		—		461
Fundamental change and make-whole interest provisions embedded in 2021 Notes		12		—		—		12
Embedded Deerfield Note Put Option		2,626						2,626
Total liabilities	$	8,311	$	—	$	—	$	8,311
Trading securities:
Certificates of deposit		8,316		8,316		—		—
U.S. Treasury securities		38,504		38,504		—		—
U.S. government-sponsored agency securities		5,502		—		5,502		—
Total assets	$	52,322	$	46,820	$	5,502	$	—

	Balance at December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	16	$	—	$	—	$	16
Deerfield Warrant liability		4,231		—		—		4,231
Embedded Warrant Put Option		365		—		—		365
Fundamental change and make-whole interest provisions embedded in 2021 Notes		6		—		—		6
Total liabilities	$	4,618	$	—	$	—	$	4,618
Trading securities:
Certificates of deposit		7,788		7,788		—		—
U.S. Treasury securities		37,066		37,066		—		—
U.S. government-sponsored agency securities		14,349		—		14,349		—
Total assets	$	59,203	$	44,854	$	14,349	$	—

The Company

’s Underwriter Warrant liability, Deerfield Warrant liability, embedded Warrant Put Option, the fundamental change and the make-whole interest provisions embedded in the

2021

Notes, and the embedded Deerfield Note Put Option, as well as the trading securities are measured at fair value on a recurring basis. As of

June 30, 2017

and

December

31,

2016,

the Underwriter Warrant liability, Deerfield Warrant liability, embedded Warrant Put Option, and the fundamental change and make-whole interest provisions embedded in the

2021

Notes are reported on the condensed balance sheet in derivative and warrant liability, while the trading securities are reported on the condensed balance sheet in marketable securities and long-term investments. A

s of

June 30, 2017,

the embedded Deerfield Note Put Option is reported on the condensed balance sheet in derivative and warrant liability. The Company used a Monte Carlo simulation to value the Underwriter Warrant liability, Deerfield Warrant liability, embedded Warrant Put Option, and the fundamental change and make-whole interest provisions embedded in the

2021

Notes at

June 30, 2017

and

December

31,

2016.

The

Company also used a Monte Carlo simulation to value the embedded Deerfield Note Put Option at

June 30, 2017.

Significant unobservable inputs used in measuring the fair value of these financial instruments included the Company’s estimated enterprise value, an estimate of the timing of a liquidity or fundamental change event, a present value discount rate and an estimate of the Company’s stock volatility using the volatilities of guideline peer companies. Changes in the fair value of the Underwriter Warrant liability, Deerfield Warrant liability, embedded Warrant Put Option, the fundamental change and make-whole interest provisions embedded in the

2021

Notes and the embedded Deerfield Note Put Option are reflected in the condensed statements of operations as a fair value adjustment.

A reconciliation of the beginning and ending balances for the derivative and warrant liability measured at fair value on a recurring basis using significant unobservable inputs

(Level

) is as follows (in thousands):

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017		2016
Balance at beginning of period	$	11,834		$	27,479		$	4,618	$	37,839
Exercise of warrants		—			(673	)		—		(755	)
Adjustment to fair value		(3,523	)		(20,763	)		3,693		(31,041	)
Balance at end of period	$	8,311		$	6,043		$	8,311	$	6,043

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Note I - Net (Loss) Income Per Share

6 Months Ended

Jun. 30, 2017

Notes to Financial Statements

Earnings Per Share [Text Block]

Net (Loss) Income Per Share

Under the

two

-class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during t

he period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed.

such adjustment to earnings is made during periods with a net loss as the holders of the participating securities have

obligation to fund losses. Diluted net (loss) income per common share is computed under the

two

-class method by using the weighted average number of shares of common stock outstanding plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, the Company analyzes the potential dilutive effect of the outstanding participating securities under the if-converted method when calculating diluted net (loss) income per share in which it is assumed that the outstanding participating securities convert into common stock at the beginning of the period. The Company reports the more dilutive of the approaches (

two

-class or if-converted) as its diluted net (loss) income per share during the period.

Diluted net loss per share

was the same as basic net loss per share for the

three

and

six

month periods ended

June 30, 2017

because the effects of potentially dilutive items were anti-dilutive given the Company's net loss for the

three

and

six

month periods ended

June 30, 2017.

The following securities, presented on a common stock equivalent basis, have been excluded from the calculation of weighted average number of shares of common stock outstanding because their effect is anti-dilutive:

	Three and Six Months Ended June 30 ,
	2017		2016
Warrants to purchase common stock		2,027,763		164,400
Awards under equity incentive plans		2,873,344		2,238,153
Deerfield Convertible Notes		1,750,954		2,088,931
2021 Notes		5,040,914		5,040,914
Total		11,692,975		9,532,398

The following table reconciles basic net income per share of common stock

to diluted net loss per share of common stock for the

three

and

six

month periods ended

June 30, 2016 (

in thousands, except per share data):

	Three Months Ended			Six Months Ended
	June 30, 2016
Basic net income per share of common stock:
Net income	$	9,768		$	6,834
Less: Net income allocable to participating securities		(1,137	)		(798	)
Net income allocable to shares of common stock		8,631			6,036
Less: Dividends declared or accumulated		—			—
Undistributed net income allocable to shares of common stock, basic	$	8,631		$	6,036
Weighted average number of shares of common stock outstanding		14,597			14,547
Basic net income per share of common stock	$	0.59		$	0.41
Diluted net loss per share of common stock:
Net income	$	9,768		$	6,834
Less: Fair value adjustment for Deerfield stock warrants		(18,769	)		(28,001	)
Net loss allocable to shares of common stock, diluted	$	(9,001	)	$	(21,167	)
Weighted average number of shares of common stock outstanding		14,597			14,547
Dilutive effect of Deerfield stock warrants		838			1,037
Weighted average number of shares of common stock outstanding, diluted		15,435			15,583
Diluted net loss per share of common stock	$	(0.58	)	$	(1.36	)

Note J - Severance Expense	6 Months Ended
Note J - Severance Expense	Jun. 30, 2017
Notes to Financial Statements
Restructuring and Related Activities Disclosure [Text Block]	J. Severance Expense On September 15, 2016, the Company announced its intention to defer its commercial operations and realign its financial resources and operational priorities towards its product development pipeline. The activities related to the deferral and realignment were completed during the year ended December 31, 2016. As part of these activities, the Company reduced its workforce by three employees. Personnel and other related charges of approximately $1.1 million and stock compensation expense of approximately $1.9 million related to the acceleration of vesting on certain stock options, related to the workforce reduction, were presented as severance expense in the statements of operations for the year ended December 31, 2016. As of June 30, 2017, the Company had accrued severance expense recorded within accounts payable and accrued expenses in the amount of $0.2 million .

Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Organization KemPharm, Inc. (the “ Company”) is a clinical-stage specialty pharmaceutical company engaged in the discovery and development of proprietary prodrugs. Through the use of its Ligand Activated Therapy (“LAT ™ ”) platform technology, the Company is able to initiate and pursue the development of improved versions of widely prescribed, approved drugs. The Company was formed and incorporated in Iowa on October 30, 2006 and reorganized in Delaware on May 30, 2014. The Company has experienced recurrin g losses from operations and negative operating cash flows due to its ongoing research and development of its potential product candidates. The Company also has an accumulated deficit at June 30, 2017. Various internal and external factors will affect whether and when the candidates become approved drugs and how significant their market share will be. The length of time and cost of developing and commercializing these candidates and/or failure of them at any stage of the drug approval process will materially affect the Company’s financial condition and future operations. The accompanying unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for inter im financial information and with the instructions to Form 10 -Q and Rule 8 - 03 of Regulation S- X. Accordingly, they do not include all of the information and related notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included in the accompanying financial statements. Operating results for the three and six months ended June 30, 2017 are not necessarily indicative of the results that may be expected for the full year ending December 31, 2017. This interim information should be read in conjunction with the audited financial statements included in the Company ’s Annual Report on Form 10 -K for the fiscal year ended December 31, 2016, filed with the Securities and Exchange Commission (“SEC”) on March 10, 2017. Initial Public Offering and Reverse Stock Split In 2015, the Company completed an initial public offering ("IPO") of its common stock. Prior to the comm encement of the IPO, the Company effected a 1 -for- 7.5 reverse stock split of its issued common stock. Upon completion of the IPO, all outstanding shares of the Company's redeemable convertible preferred stock were converted or reclassified into shares of common stock and all outstanding warrants to acquire shares of the Company's redeemable convertible preferred stock became warrants to acquire the Company's common stock. In connection with the IPO, the Company amended and restated its Amended and Restated Certificate of Incorporation to change the authorized capital stock to 250,000,000 shares designated as common stock, and 10,000,000 shares designated as preferred stock, each with a par value of $0.0001 per share.
Reclassification, Policy [Policy Text Block]	Reclassifications During the second quarter of 2017, the Company early adopted Accounting Standards Update (“ASU”) 2016 - 18, Statements of Cash Flows (Topic 320 ) – Restricted Cash ("ASU 2016 - 18" ), which addresses the treatment of restricted cash and restricted cash equivalents in the statement of cash flows . The adoption of ASU 2016 - 18 reduced the Company’s net cash used in investing activities and net decrease in cash and cash equivalents on the condensed statements of cash flows by $1.1 million for the six months ended June 30, 2016, as compared to the net cash used in investing activities and net decrease in cash and cash equivalents on the condensed statements of cash flows if the Company had not early adopted ASU 2016 - 18. This reclassification had no effect on the condensed balance sheets or statements of operations.
Stockholders' Equity, Policy [Policy Text Block]	Entry into ATM Agreement On October 3, 2016, the Company entered into a Common Stock Sales Agreement (the "ATM Agreement") with Cowen and Company, LLC ("Cowen") under which the Company may offer and sell, from time to time, in its sole discretion, shares of common stock having an aggregate offering price of up to $50,000,000 through Cowen as the Company's sales agent. The Company's registration statement on Form S- 3 contemplated under the ATM Agreement was declared effective by the SEC on October 17, 2016. The registration statement on Form S- 3 included a prospectus covering the offering up to $20,000,000 of shares of common stock in accordance with the ATM Agreement. Cowen may sell common stock under the ATM Agreement by any method permitted by law deemed to be an "at the market offering" as defined in Rule 415 of the Securities Act, including without limitation sales made by means of ordinary brokers' transactions on The NASDAQ Global Market or otherwise at market prices prevailing at the time of sale, in block transactions, or as otherwise directed by the Company. Cowen will use commercially reasonable efforts to sell the common stock from time to time, based upon instructions from the Company (including any price, time or size limits or other customary parameters or conditions the Company may impose). The Company will pay Cowen a commission of up to 3.0% of the gross sales proceeds of any common stock sold through Cowen under the ATM Agreement, and has provided Cowen with customary indemnification rights. The Company is not obliga ted to make any sales of common stock under the ATM Agreement. The offering of shares of common stock pursuant to the ATM Agreement will terminate upon the earlier of (i) the sale of all common stock subject to the ATM Agreement, or (ii) termination of the ATM Agreement in accordance with its terms. As of June 30, 2017, the Company has made no sales of its common stock pursuant to the terms of the ATM Agreement and had deferred offering costs related to the offering contemplated by the ATM Agreement recorded within prepaid and other current assets and other long-term assets in the amount of $0.2 million.
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those rel ated to the useful lives of property and equipment, and assumptions used for purposes of determining stock-based compensation, income taxes, and the fair value of the derivative and warrant liability, among others. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable, the results of which form the basis for making judgments about the carrying value of assets and liabilities.
New Accounting Pronouncements, Policy [Policy Text Block]	Application of New or Revised Accounting Standards —Adopted From time to time, the Financial Accounting Standards Board (the “ FASB”) or other standard-setting bodies issue accounting standards that are adopted by the Company as of the specified effective date. On April 5, 2012, President Obama signed the Jump-Sta rt Our Business Startups Act (the “JOBS Act”) into law. The JOBS Act contains provisions that, among other things, reduce certain reporting requirements for an emerging growth company. As an emerging growth company, the Company could have elected to adopt new or revised accounting standards when they become effective for non-public companies, which typically is later than public companies must adopt the standards. The Company elected not to take advantage of the extended transition period afforded by the JOBS Act and, as a result, will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for non-emerging growth companies. In November 2015, the FASB issued ASU 2 015 - 17, Income Taxes: Balance Sheet Classification of Deferred Taxes (Topic 740 ) ("ASU 2015 - 17" ), which requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. This update applies to all entities that present a classified statement of financial position. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The adoption of ASU 2015 - 17 did not have a material impact on Company's financial statements and disclosures as the Company maintains a full valuation allowance. In March 2016, the FASB issued ASU 2016 - 06, Derivatives and Hedging (Topic 815 ), Contingent Put and Call Options in Debt Instruments ("ASU 2016 - 06" ), which clarifies the requirements for assessing whether contingent call and put options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. ASU 2016 - 06 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years, with early adoption permitted. The adoption of ASU 2016 - 06 did not have a material impact on Company's financial statements and disclosures. In March 2016, the FASB issued ASU 2016 - 09, Compensation–Stock Compensation (Topic 718 ), Improvements to Employee Share-Based Payment Accounting ("ASU 2016 - 09" ), which simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016 - 09 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years, with early adoption permitted. The adoption of ASU 2016 - 09 did not have a material impact on Company's financial statements and disclosures. In November 2016, the FASB issued ASU 2016 - 18, which applies to all entities that have restricted cash or restricted cash equivalents and are required to present a statement of cash flows. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company early adopted ASU 2016 - 18 in the current quarter. Refer to Note A for discussion regarding the impact the adoption of ASU 2016 - 18 had on the Company's financial statements and disclosures.
New Accounting Pronouncements, Not Yet Adopted, Policy [Policy Text Block]	Application of New or Revised Accounting Standards —Not Yet Adopted In May 2014, the FASB issued guidance codified in Accounting Standard Codification ("ASC") Topic 606, Revenue Recognition—Revenue from Contracts with Customers ("ASC 606" ), which amends the guidance in former ASC 605, Revenue Recognition , and becomes effective beginning January 1, 2018. The Company does not currently expect this standard to have a material effect on its financial statements upon adoption since the Company is not generating revenue at this time. In January 2016, the FASB issued ASU 2016 - 01 , Financial Instruments Overall – Recognition and Measurement of Financial Assets and Liabilities (Topic 825 - 10 ) (“ASU 2016 - 01” ), which provides several updates related to Topic 825 - 10. This update applies to all entities that hold financial assets or owe financial liabilities. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2016 - 01 on its financial statements and disclosures. In February 2016, the FASB issued ASU 2016 - 02, Leases (Topic 842 ) (“ASU 2016 - 02” ), which requires lessees to recognize assets and liabilities for operating leases with lease terms greater than twelve months in the balance sheet. The update also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. ASU 2016 - 02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the adoption of ASU 2016 - 02 on its financial statements and disclosures. In August 2016, the FASB issued ASU 2016 - 15, Statement of Cash Flows – Classification of Certain Cash Receipts and Cash Payments (Topic 230 ) (“ASU 2016 - 15” ), which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. This update applies to all entities that are required to present a statement of cash flows under Topic 230. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2016 - 15 on its financial statements and disclosures. In May 2017, the FASB issued ASU 2017 - 09, Compensation – Stock Compensation (Topic 718 ) – Scope of Modification Accounting ("ASU 2017 - 09" ), which provides guidance about which changes to the terms or conditions of a stock-based payment award require an entity to apply modification accounting in Topic 718. This update applies to any entity that changes the terms or conditions of a stock-based payment award. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2017 - 09 on its financial statements and disclosures. In July 2017, the FASB issued ASU 2017 - 11, Earnings Per Share (Topic 260 ), Distinguishing Liabilities from Equity (Topic 480 ), Derivatives and Hedging (Topic 815 ) – I. Accounting for Certain Financial Instruments with Down Round Features and II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception ("ASU 2017 - 11" ), which addresses the complexity of accounting for certain financial instruments with down round features and addresses the difficulty of navigating Topic 480 because of the existence of extensive pending content in the ASC as a result of the indefinite deferral of accounting requirements about mandatorily redeemable financial instruments of certain nonpublic entities and certain mandatorily redeemable noncontrolling interests . This update applies to all entities that issue financial instruments that include down round features and entities that present earnings per share in accordance with Topic 260. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of ASU 2017 - 11 on its financial statements and disclosures.

Note F - Common Stock and Warrants (Tables)

6 Months Ended

Jun. 30, 2017

Notes Tables

Schedule of Authorized Shares of Common Stock Reserved for Future Issuance [Table Text Block]

	June 3 0 , 2017		December 31, 2016
Conversion of Deerfield Convertible Notes		1,750,954		1,751,296
Conversion of 2021 Notes		5,040,914		5,040,914
Outstanding awards under equity incentive plans		2,873,344		1,990,260
Outstanding common stock warrants		2,027,763		2,087,477
Possible future issuances under equity incentive plans		928,800		1,244,671
Total common shares reserved for future issuance		12,621,775		12,114,618

Schedule of Common Stock Outstanding Roll Forward [Table Text Block]

	Shares of Common Stock
Balance at December 31, 2016		14,646,982
Common stock warrants exercised		698
Common stock options exercised		9,750
Balance at June 30, 2017		14,657,430

Note G - Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2017

Notes Tables

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Research and development	$	340	$	268	$	631	$	455
General and administrative		825		989		1,623		1,824
Total		1,165	$	1,257		2,254	$	2,279

Note H - Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2017

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Balance at June 30 , 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Deerfield Warrant liability		5,212		—		—		5,212
Embedded Warrant Put Option		461		—		—		461
Fundamental change and make-whole interest provisions embedded in 2021 Notes		12		—		—		12
Embedded Deerfield Note Put Option		2,626						2,626
Total liabilities	$	8,311	$	—	$	—	$	8,311
Trading securities:
Certificates of deposit		8,316		8,316		—		—
U.S. Treasury securities		38,504		38,504		—		—
U.S. government-sponsored agency securities		5,502		—		5,502		—
Total assets	$	52,322	$	46,820	$	5,502	$	—

	Balance at December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	16	$	—	$	—	$	16
Deerfield Warrant liability		4,231		—		—		4,231
Embedded Warrant Put Option		365		—		—		365
Fundamental change and make-whole interest provisions embedded in 2021 Notes		6		—		—		6
Total liabilities	$	4,618	$	—	$	—	$	4,618
Trading securities:
Certificates of deposit		7,788		7,788		—		—
U.S. Treasury securities		37,066		37,066		—		—
U.S. government-sponsored agency securities		14,349		—		14,349		—
Total assets	$	59,203	$	44,854	$	14,349	$	—

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017		2016
Balance at beginning of period	$	11,834		$	27,479		$	4,618	$	37,839
Exercise of warrants		—			(673	)		—		(755	)
Adjustment to fair value		(3,523	)		(20,763	)		3,693		(31,041	)
Balance at end of period	$	8,311		$	6,043		$	8,311	$	6,043

Note I - Net (Loss) Income Per Share (Tables)

6 Months Ended

Jun. 30, 2017

Notes Tables

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Three and Six Months Ended June 30 ,
	2017		2016
Warrants to purchase common stock		2,027,763		164,400
Awards under equity incentive plans		2,873,344		2,238,153
Deerfield Convertible Notes		1,750,954		2,088,931
2021 Notes		5,040,914		5,040,914
Total		11,692,975		9,532,398

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Three Months Ended			Six Months Ended
	June 30, 2016
Basic net income per share of common stock:
Net income	$	9,768		$	6,834
Less: Net income allocable to participating securities		(1,137	)		(798	)
Net income allocable to shares of common stock		8,631			6,036
Less: Dividends declared or accumulated		—			—
Undistributed net income allocable to shares of common stock, basic	$	8,631		$	6,036
Weighted average number of shares of common stock outstanding		14,597			14,547
Basic net income per share of common stock	$	0.59		$	0.41
Diluted net loss per share of common stock:
Net income	$	9,768		$	6,834
Less: Fair value adjustment for Deerfield stock warrants		(18,769	)		(28,001	)
Net loss allocable to shares of common stock, diluted	$	(9,001	)	$	(21,167	)
Weighted average number of shares of common stock outstanding		14,597			14,547
Dilutive effect of Deerfield stock warrants		838			1,037
Weighted average number of shares of common stock outstanding, diluted		15,435			15,583
Diluted net loss per share of common stock	$	(0.58	)	$	(1.36	)

Note A - Description of Business and Basis of Presentation (Details Textual)		6 Months Ended
	Apr. 02, 2015	Jun. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) $ / shares shares	Oct. 17, 2016 USD ($)	Oct. 03, 2016 USD ($)	Dec. 31, 2015 USD ($)	May 31, 2015 $ / shares shares	Apr. 30, 2015 shares
Common Stock, Shares Authorized \| shares		250,000,000		250,000,000				250,000,000	250,000,000
Preferred Stock, Shares Authorized \| shares		10,000,000		10,000,000				10,000,000
Common Stock, Par or Stated Value Per Share \| $ / shares		$ 0.0001		$ 0.0001				$ 0.0001
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		$ 11,741,000	$ (55,201,000)
Preferred Stock, Par or Stated Value Per Share \| $ / shares		$ 0.0001		$ 0.0001				$ 0.0001
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		$ 13,486,000	28,610,000	$ 17,862,000			$ 32,318,000
Other Noncurrent Assets [Member]
Deferred Offering Costs		$ 200,000
Cowen and Company, LLC [Member]
Sale of Stock, Authorized Offering Price					$ 20,000,000
Sale of Stock, Commission Fee					3.00%
Cowen and Company, LLC [Member] \| Maximum [Member]
Sale of Stock, Authorized Offering Price						$ 50,000,000
Accounting Standards Update 2016-18 [Member]
Net Cash Provided by (Used in) Investing Activities, Continuing Operations			1,100,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents			$ 1,100,000
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	7.5

Note C - Debt Obligations (Details Textual) - USD ($)			6 Months Ended
Note C - Debt Obligations (Details Textual) - USD ($)	Feb. 09, 2016	Jun. 02, 2014	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2013
Series D Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					1,079,453
2021 Notes [Member]
Debt Instrument, Face Amount	$ 86,300,000
Debt Instrument, Interest Rate, Stated Percentage	5.50%
Proceeds from Debt, Net of Issuance Costs	$ 82,800,000
Repayments of Long-term Debt	18,600,000
Debt Instrument, Sinking Fund Payment	$ 0
Debt Conversion, Converted Instrument, Shares Issued	58.4454
Debt Conversion, Original Debt, Amount	$ 1,000
Debt Instrument, Convertible, Conversion Price	$ 17.11
Debt Instrument Repurchase Price Equal to Percentage of Principal Amount	100.00%
Deerfield Facility Agreement [Member]
Debt Covenant, Debt Financing Restriction		$ 750,000
Line of Credit Facility, Maximum Borrowing Capacity		$ 60,000,000
Line of Credit Facility, Interest Rate at Period End		9.75%
Deerfield Facility Agreement [Member] \| IPO [Member]
Reclassification of Common Stock Shares		256,410
Deerfield Facility Agreement [Member] \| Deerfield Warrant [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 0.78
Deerfield Facility Agreement [Member] \| Deerfield Warrant [Member] \| IPO [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		1,923,077
Deerfield Facility Agreement [Member] \| Series D Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		14,423,076
Own-share Lending Arrangement, Shares, Issued		1,923,077
Mandatorily Redeemable Preferred Stock, Fair Value Disclosure		$ 1,500,000
Deerfield Facility Agreement [Member] \| Term Notes [Member]
Proceeds from Secured Notes Payable		$ 15,000,000
Deerfield Facility Agreement [Member] \| Deerfield Convertible Notes [Member]
Debt Instrument, Convertible, Conversion Price		$ 5.85
Proceeds from Secured Notes Payable		$ 10,000,000
Third Line of Credit Agreement [Member] \| City National Bank of Florida [Member]
Line of Credit Facility, Remaining Borrowing Capacity			$ 400,000
Long-term Line of Credit			$ 0
Line of Credit Facility, Maximum Borrowing Capacity				$ 1,100,000
Third Line of Credit Agreement [Member] \| City National Bank of Florida [Member] \| Prime Rate [Member]
Debt Instrument, Basis Spread on Variable Rate			2.00%
Debt Instrument, Interest Rate, Stated Percentage			3.06%

Note D - Commitments and Contingencies (Details Textual) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Loss Contingency Accrual	$ 0	$ 0

Note E - Preferred Stock and Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Jun. 02, 2014	Dec. 31, 2013	Jun. 30, 2017	Dec. 31, 2016	May 31, 2015
Preferred Stock, Shares Authorized			10,000,000	10,000,000	10,000,000
Preferred Stock, Shares Outstanding			0	0
Common Stock [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 5.85
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		143,466
Series D Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		1,079,453
2013 Warrants [Member]
Class of Warrant or Right Issued		1,079,453
Deerfield Warrant [Member]
Class of Warrant or Right Issued	14,423,076
Deerfield Warrant [Member] \| Common Stock [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 5.85
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	1,923,077
Convertible Notes Payable [Member]
Debt Instrument, Face Amount		$ 3.8

Note F - Common Stock and Warrants (Details Textual) - shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	May 31, 2015	Apr. 30, 2015	Dec. 31, 2012
Common Stock, Shares Authorized	250,000,000		250,000,000	250,000,000	250,000,000
Common Stock, Shares, Issued	14,657,430		14,646,982
Common Stock Issued During Period from Warrants Exercised	698	141,095
Common Stock, Shares, Outstanding	14,657,430		14,646,982
Private Placement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						595,920

Note F - Common Stock and Warrants - Reserved Authorized Shares of Common Stock for Future Issuance (Details) - shares	Jun. 30, 2017	Dec. 31, 2016
Common shares reserved for future issuance (in shares)	12,621,775	12,114,618
Warrant [Member]
Common shares reserved for future issuance (in shares)	2,027,763	2,087,477
Stock Compensation Plan [Member]
Common shares reserved for future issuance (in shares)	2,873,344	1,990,260
Possible Future Issuances Under Equity Incentive Plans [Member]
Common shares reserved for future issuance (in shares)	928,800	1,244,671
2021 Notes [Member]
Common shares reserved for future issuance (in shares)	5,040,914	5,040,914
Convertible Notes Payable [Member]
Common shares reserved for future issuance (in shares)	1,750,954	1,751,296

Note F - Common Stock and Warrants - Common Stock Activity (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Balance (in shares)			14,646,982
Common stock warrants exercised (in shares)			698	141,095
Common stock options exercised (in shares)	9,250	14,933	9,250	14,933
Balance (in shares)	14,657,430		14,657,430

Note G - Stock-based Compensation (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	9,250	14,933	9,250	14,933
Allocated Share-based Compensation Expense	$ 1,165,000	$ 1,257,000	$ 2,254,000	$ 2,279,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares				13,333
Research and Development Expense [Member]
Allocated Share-based Compensation Expense	340,000	268,000	631,000	$ 455,000
Performance Shares [Member] \| Research and Development Expense [Member]
Allocated Share-based Compensation Expense	$ 0	$ 0	$ 0	$ 29,000
2014 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	3,432,183		3,432,183
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Reserved for Issuance, Incremental Percentage of Capital Stock Outstanding			4.00%
Increase in Common Stock Reserved for Issuance			585,879

Note G - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock based compensation expense	$ 1,165	$ 1,257	$ 2,254	$ 2,279
Research and Development Expense [Member]
Stock based compensation expense	340	268	631	455
General and Administrative Expense [Member]
Stock based compensation expense	$ 825	$ 989	$ 1,623	$ 1,824

Note H - Fair Value of Financial Instruments (Details Textual) - Fair Value, Inputs, Level 3 [Member] - Deerfield Facility Agreement [Member] - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Deerfield Convertible Notes [Member]
Long-term Debt, Fair Value	$ 11.0	$ 10.2
Term Notes [Member]
Long-term Debt, Fair Value	$ 50.0	$ 46.3

Note H - Fair Value of Financial Instruments - Reconciliation of Beginning and Ending Balances for Derivative and Warrant Liability Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Balance at beginning of period	$ 11,834	$ 27,479	$ 4,618	$ 37,839
Exercise of warrants		(673)		(755)
Adjustment to fair value	(3,523)	(20,763)	3,693	(31,041)
Balance at end of period	$ 8,311	$ 6,043	$ 8,311	$ 6,043

Note I - Net (Loss) Income Per Share - Anti-dilutive Securities (Details) - shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Antidilutive securities (in shares)	11,692,975	9,532,398
Warrants to Purchase Common Stock [Member]
Antidilutive securities (in shares)	2,027,763	164,400
Stock Compensation Plan [Member]
Antidilutive securities (in shares)	2,873,344	2,238,153
Convertible Debt Securities [Member]
Antidilutive securities (in shares)	1,750,954	2,088,931
2021 Notes [Member]
Antidilutive securities (in shares)	5,040,914	5,040,914

Note I - Net (Loss) Income Per Share - Reconciliation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basic net income per share of common stock:
Basic net income per share of common stock (in dollars per share)	$ (0.44)	$ 0.59	$ (1.56)	$ 0.41
Diluted net loss per share of common stock:
Net income	$ (6,517)	$ 9,768	$ (22,839)	$ 6,834
Less: Net income allocable to participating securities		(1,137)		(798)
Net income allocable to shares of common stock		8,631		6,036
Less: Dividends declared or accumulated
Undistributed net income allocable to shares of common stock, basic		$ 8,631		$ 6,036
Weighted average number of shares of common stock outstanding (in shares)	14,649,586	14,597,449	14,648,291	14,546,576
Less: Fair value adjustment for Deerfield stock warrants		$ (18,769)		$ (28,001)
Net loss allocable to shares of common stock, diluted		$ (9,001)		$ (21,167)
Weighted average number of shares of common stock outstanding (in shares)	14,649,586	14,597,449	14,648,291	14,546,576
Dilutive effect of Deerfield stock warrants (in shares)		838,000		1,037,000
Weighted average number of shares of common stock outstanding, diluted (in shares)	14,649,586	15,435,322	14,648,291	15,583,390
Diluted net loss per share of common stock (in dollars per share)	$ (0.44)	$ (0.58)	$ (1.56)	$ (1.36)

Note J - Severance Expense (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
Note J - Severance Expense (Details Textual) $ in Thousands	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Restructuring and Related Cost, Number of Positions Eliminated					3
Allocated Share-based Compensation Expense	$ 1,165	$ 1,257	$ 2,254	$ 2,279
Employee Severance [Member] \| Accounts Payable and Accrued Liabilities [Member]
Restructuring Reserve	$ 200		$ 200
Employee Severance [Member] \| Severance Expense [Member]
Restructuring Charges					$ 1,100
Allocated Share-based Compensation Expense					$ 1,900

Note H - Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial liabilities measured at fair value on recurring basis	$ 8,311	$ 4,618
Financial assets measured at fair value on recurring basis	52,322	59,203
Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis	8,316	7,788
US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis	38,504	37,066
US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis	5,502	14,349
Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Financial assets measured at fair value on recurring basis	46,820	44,854
Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis	8,316	7,788
Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis	38,504	37,066
Fair Value, Inputs, Level 1 [Member] \| US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Financial assets measured at fair value on recurring basis	5,502	14,349
Fair Value, Inputs, Level 2 [Member] \| Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 2 [Member] \| US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis	5,502	14,349
Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	8,311	4,618
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 3 [Member] \| Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 3 [Member] \| US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 3 [Member] \| US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis
Deerfield Warrant Liability [Member]
Financial liabilities measured at fair value on recurring basis	5,212	4,231
Deerfield Warrant Liability [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Deerfield Warrant Liability [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Deerfield Warrant Liability [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	5,212	4,231
Underwriter Warrant Liability [Member]
Financial liabilities measured at fair value on recurring basis		16
Underwriter Warrant Liability [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Underwriter Warrant Liability [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Underwriter Warrant Liability [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis		16
Embedded Put Option [Member]
Financial liabilities measured at fair value on recurring basis	461	365
Embedded Put Option [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Embedded Put Option [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Embedded Put Option [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	461	365
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member]
Financial liabilities measured at fair value on recurring basis	12	6
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	12	$ 6
Embedded Deerfield Note Put Option [Member]
Financial liabilities measured at fair value on recurring basis	2,626
Embedded Deerfield Note Put Option [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Embedded Deerfield Note Put Option [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Embedded Deerfield Note Put Option [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	$ 2,626