Note 1 - Summary of Significant Accounting Policies - Summary of Deferred Compensation Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred compensation plan assets	$ 53,172	$ 46,146
Deferred compensation plan liabilities	55,771	48,435
Other Long-term Assets [Member]
Deferred compensation plan assets	53,172	46,146
Accrued Compensation and Related Benefits [Member]
Deferred compensation plan liabilities	282	155
Other Long-term Liabilities [Member]
Deferred compensation plan liabilities	55,489	48,280
Cash Surrender Value [Member]
Deferred compensation plan assets	21,386	19,222
Mutual Funds and Money Market Funds, Fair Value [Member]
Deferred compensation plan assets	$ 31,786	$ 26,924