Note 5 - Share-based Compensation - Components of Share-based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted Stock Units (RSUs) [Member]
Pretax compensation expense	$ 56,837	$ 54,276	$ 44,505
Tax benefit	12,561	13,216	10,637
Restricted share units, net of tax	44,276	41,060	33,868
Performance Shares [Member]
Pretax compensation expense	22,352	23,259	17,000
Tax benefit	4,940	5,664	4,063
Restricted share units, net of tax	$ 17,412	$ 17,595	$ 12,937