Note 10 - Capital Resources (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	7 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2025	Feb. 28, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Jun. 04, 2025	May 28, 2024	Dec. 31, 2022
Equity, Attributable to Parent	$ 2,925,388		$ 2,925,388	$ 2,845,704	$ 2,736,575			$ 2,474,040
Stockholders' Equity, Period Increase (Decrease)			$ 79,700
Stockholders' Equity, Period Increase (Decrease), Percentage			2.80%
Net Income (Loss) Attributable to Parent			$ 315,124	285,979	354,124
Other Comprehensive Income (Loss), Net of Tax			31,207	(191)	16,879
Share-Based Payment Arrangement, Expense			6,600
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan			2,610	2,933	3,491
Stock Issued During Period, Value, Issued for Services			1,000
Treasury Stock, Value, Acquired, Cost Method			180,288	84,703	16,667
Dividends, Common Stock, Cash			93,800	97,967	98,638
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation			$ 2,779	$ 3,726	$ 4,490
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share)			$ 1.36	$ 1.36	$ 1.36
Stock Repurchase Program Authorized June 4, 2025 [Member]
Treasury Stock, Value, Acquired, Cost Method	$ 137,500
Share Repurchase Program, Authorized, Amount						$ 150,000
Treasury Stock, Shares, Acquired (in shares)	2,973,982
Shares Acquired, Average Cost Per Share (in dollars per share)	$ 46.24
Stock Repurchase Program Authorized May 28, 2024 [Member]
Share Repurchase Program, Authorized, Amount							$ 125,000
Treasury Stock, Shares, Acquired (in shares)		2,905,487
Shares Acquired, Average Cost Per Share (in dollars per share)		$ 43.02