Earnings Per Share (Computation of Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net income to common shareholders	$ 460,815	$ 392,602	$ 524,089
Net income or dividends allocated to participating securities - basic and diluted	3,027	4,014	7,620
Net income allocated to common shareholders - basic	457,788	388,588	516,469
Net income allocated to common shareholders - diluted	$ 457,788	$ 388,588	$ 516,469
Weighted-average common shares - basic	86,346	86,130	86,068
Dilutive potential common shares	302	293	326
Weighted average common shares - diluted	86,648	86,423	86,394
Earnings per common share: Basic	$ 5.3	$ 4.51	$ 6
Earnings per common share: Diluted	$ 5.28	$ 4.5	$ 5.98