Earnings Per Common Share (Computation of Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share [Abstract]
Net income to common shareholders	$ 115,572	$ 97,738	$ 338,741	$ 341,999
Net income allocated to participating securities - basic and diluted	772	992	2,366	3,574
Net income allocated to common shareholders - basic	114,800	96,746	336,375	338,425
Net income allocated to common shareholders - diluted	$ 114,800	$ 96,746	$ 336,375	$ 338,425
Weighted-average common shares - basic	86,234	86,131	86,421	86,082
Dilutive potential common shares	326	306	229	286
Weighted-average common shares - diluted	86,560	86,437	86,650	86,368
Earnings per common share: Basic	$ 1.33	$ 1.12	$ 3.89	$ 3.93
Earnings per common share: Diluted	$ 1.33	$ 1.12	$ 3.88	$ 3.92