Note 11 - Capital Resources (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		7 Months Ended	12 Months Ended
	Feb. 21, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	May 26, 2022	Dec. 31, 2020
Equity, Attributable to Parent		$ 2,474,040	$ 2,736,575	$ 2,474,040	$ 2,446,251		$ 2,418,144
Stockholders' Equity, Period Increase (Decrease)			$ 262,500
Stockholders' Equity, Period Increase (Decrease), Percentage			10.60%
Net Income (Loss) Attributable to Parent			$ 354,124	360,642	298,304
Other Comprehensive Income (Loss), Net of Tax			16,879	(99,230)	(8,375)
Share-Based Payment Arrangement, Expense			7,000
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan			3,491	3,720	3,563
Stock Issued During Period, Value, Issued for Services			850	849	850
Dividends, Common Stock, Cash			98,638	100,955	99,322
Treasury Stock, Value, Acquired, Cost Method	$ 16,600	$ 108,400	16,667	141,315	167,104
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation			$ 4,490	$ 2,905	$ 2,632
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share)			$ 1.36	$ 1.36	$ 1.27
Stock Repurchase Program, Authorized Amount						$ 125,000
Treasury Stock, Shares, Acquired (in shares)	375,090	2,522,538		3,227,465
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)	$ 44.2	$ 42.98		$ 43.79
Restricted Stock Units (RSUs) [Member]
Share-Based Payment Arrangement, Expense			$ 7,000	$ 7,000	$ 6,000
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation			$ 4,500