Note 11 - Capital Resources (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	7 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Sep. 02, 2021	Dec. 31, 2019
Stockholders' Equity Attributable to Parent, Ending Balance		$ 2,474,040	$ 2,474,040	$ 2,446,251	$ 2,418,144		$ 2,294,283
Stockholders' Equity, Period Increase (Decrease), Total			$ 27,800
Stockholders' Equity, Period Increase (Decrease), Percentage			1.10%
Net Income (Loss) Attributable to Parent, Total			$ 360,642	298,304	228,860
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan			3,720	3,563	9,777
Share-Based Payment Arrangement, Expense			7,000
Other Comprehensive Income (Loss), Net of Tax, Total			(99,230)	(8,375)	3,008
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation			2,905	2,632	1,911
Treasury Stock, Value, Acquired, Cost Method	$ 32,900	$ 108,400	141,315	167,104	23,593
Dividends, Common Stock, Cash			$ 100,955	$ 99,322	$ 98,688
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share)			$ 1.36	$ 1.27	$ 1.24
Treasury Stock, Shares, Acquired (in shares)	704,927	2,522,538	3,227,465
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)	$ 46.67	$ 42.98	$ 43.79
Stock Repurchase Program, Authorized Amount						$ 125,000
Restricted Stock Units (RSUs) [Member]
Share-Based Payment Arrangement, Expense			$ 7,000	$ 6,000	$ 5,600
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation			$ 2,900