Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings per common share
Net income	$ 86,824	$ 74,262	$ 91,007	$ 94,301	$ 161,086	$ 185,307
Preferred stock dividends	(2,875)		(4,875)		(5,750)	(10,082)
Net income available to common equity	83,949		86,131		155,336	175,226
Common shareholder dividends	(30,126)		(27,620)		(60,499)	(55,280)
Unvested share-based payment awards	(205)		(203)		(415)	(412)
Undistributed earnings	53,618		58,309		94,422	119,533
Undistributed earnings allocated to common shareholders	53,257		57,887		93,807	118,722
Undistributed earnings allocated to unvested share-based payment awards	361		422		615	810
Undistributed earnings	53,618		58,309		94,422	119,533
Basic
Distributed earnings to common shareholders	30,126		27,620		60,499	55,280
Undistributed earnings allocated to common shareholders	53,257		57,887		93,807	118,722
Total common shareholders earnings, basic	83,383		85,506		154,306	174,002
Diluted
Distributed earnings to common shareholders	30,126		27,620		60,499	55,280
Undistributed earnings allocated to common shareholders	53,257		57,887		93,807	118,722
Total common shareholders earnings, diluted	$ 83,383		$ 85,506		$ 154,306	$ 174,002
Weighted average common shares outstanding	149,083		152,042		148,933	152,198
Effect of dilutive common stock awards	1,121		1,339		1,332	1,275
Diluted weighted average common shares outstanding	150,203		153,381		150,265	153,473
Basic earnings per common share	$ 0.56		$ 0.56		$ 1.04	$ 1.14
Diluted earnings per common share	$ 0.56		$ 0.56		$ 1.03	$ 1.13