Note 6 - Unearned Revenue (Details Textual) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Revenue, Remaining Performance Obligation, Amount	$ 2,491,537	$ 2,595,085	$ 3,171,552
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-04-01
Revenue, Remaining Performance Obligation, Amount	$ 2,000,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Month)	12 months