Note 18 - Stockholders' Equity (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Stockholders' Equity Attributable to Parent, Ending Balance	$ 2,431,532	$ 2,452,357	$ 2,431,532	$ 2,452,357	$ 2,422,230	$ 2,446,251	$ 2,460,948	$ 2,418,144
Stockholders' Equity, Period Increase (Decrease), Total			(14,700)
Net Income (Loss) Attributable to Parent, Total	88,978	77,199	164,006	150,583
Share-Based Payment Arrangement, Noncash Expense, Total			3,400
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan			1,873	1,725
Stock Issued During Period, Value, Issued for Services	849	850	849	850
Other Comprehensive Income (Loss), Net of Tax, Total	(25,351)	686	(68,263)	(2,938)
Treasury Stock, Value, Acquired, Cost Method	30,588	63,529	63,484	63,529
Dividends, Common Stock, Cash	25,537	24,548	51,052	49,198
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 1,730	$ 1,315	$ 2,015	$ 2,594