Note 11 - Stockholders' Equity and Stock Incentive Plans - Share-based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based compensation expense	$ 25,202	$ 25,379	$ 17,413
Share-based Payment Arrangement, Option [Member]
Share-based compensation expense	52	154	1,193
Restricted Stock Units (RSUs) [Member]
Share-based compensation expense	14,301	10,219	7,463
Performance Shares [Member]
Share-based compensation expense	9,525	13,647	7,381
Career Shares [Member]
Share-based compensation expense	$ 1,324	$ 1,359	$ 1,376

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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