Note H - Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financial liabilities measured at fair value on recurring basis	$ 6,999	$ 4,618
Financial assets measured at fair value on recurring basis	44,129	59,203
Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis	7,581	7,788
US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis	31,043	37,066
US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis	5,505	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	38,624	44,854
Fair Value, Inputs, Level 1 [Member] | Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis	7,581	7,788
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis	31,043	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	5,505	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	5,505	14,349
Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	6,999	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	4,481	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	4,481	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	480	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	480	365
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member]
Financial liabilities measured at fair value on recurring basis	9	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	9	$ 6
Embedded Deerfield Note Put Option [Member]
Financial liabilities measured at fair value on recurring basis	2,029
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	$ 2,029