Earnings Per Common Share (Computation of Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net income to common shareholders	$ 114,557	$ 117,794	$ 223,169	$ 244,261
Net income allocated to participating securities - basic and diluted	810	1,224	1,594	2,582
Net income allocated to common shareholders - basic	113,747	116,570	221,575	241,679
Net income allocated to common shareholders - diluted	$ 113,747	$ 116,570	$ 221,575	$ 241,679
Weighted-average common shares - basic	86,510	86,096	86,515	86,057
Dilutive potential common shares	255	274	253	293
Weighted-average common shares - diluted	86,765	86,370	86,768	86,350
Earnings per common share: Basic	$ 1.31	$ 1.35	$ 2.56	$ 2.81
Earnings per common share: Diluted	$ 1.31	$ 1.35	$ 2.55	$ 2.80