Note 8 - Fair Value Measurement - Schedule of Carrying and Fair Value Amounts (Details) - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Held-to-maturity marketable securities (1)	[1]	$ 15,600	$ 5,200
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
2.75% Convertible Notes	[2],[3]	207,354	200,303
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Term Loan [Member]
Notes	[3]	123,750	131,250
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Held-to-maturity marketable securities (1)	[1]	15,459	5,200
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
2.75% Convertible Notes	[2],[3]	313,785	248,400
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Term Loan [Member]
Notes	[3]	$ 124,598	$ 133,030

[1] All marketable securities were classified as held-to-maturity and consisted of U.S. Government and agency obligations as of December 31, 2021 and 2020.

[2] Excluded from carrying value is $22.6 million and $29.7 million of debt discount as of December 31, 2021 and 2020, respectively, related to the 2.75% Convertible Notes (see Note 14).

[3] The fair value of the 2.75% Convertible Notes is based on the median price of the notes in an active market as of December 31, 2021 and 2020. The fair value of the Credit Agreement term loan is based on borrowing rates available to us for long-term loans with similar terms, average maturities, and credit risk. See Note 14 for definitions of, and more information about the 2.75% Convertible Notes and Credit Agreement.