Earnings Per Common Share (Computation of Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net income to common shareholders	$ 108,612	$ 126,467
Net income allocated to participating securities - basic and diluted	784	1,358
Net income allocated to common shareholders - basic	107,828	125,109
Net income allocated to common shareholders - diluted	$ 107,828	$ 125,109
Weighted-average common shares - basic	86,521	86,018
Dilutive potential common shares	205	264
Weighted-average common shares - diluted	86,726	86,282
Earnings per common share: Basic	$ 1.25	$ 1.45
Earnings per common share: Diluted	$ 1.24	$ 1.45