Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Series F Preferred Stock	Series G Preferred Stock	Preferred Stock	Common Stock	Paid-In Capital	Retained Earnings	Retained Earnings Series F Preferred Stock	Retained Earnings Series G Preferred Stock	Treasury Stock, at cost	Accumulated Other Comprehensive Income (Loss), Net of Tax
Beginning Balance at Dec. 31, 2020	$ 3,234,625			$ 145,037	$ 937	$ 1,109,532	$ 2,077,522			$ (140,659)	$ 42,256
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	202,113						202,113
Other comprehensive (loss), net of tax	(36,366)										(36,366)
Common stock dividends and equivalents	(72,537)						(72,537)
Preferred stock dividends		$ (3,938)						$ (3,938)
Stock-based compensation	6,433					(3,311)				9,744
Exercise of stock options	3,386					(5,095)				8,481
Common shares acquired from stock compensation plan activity	(4,011)									(4,011)
Ending Balance at Jun. 30, 2021	3,329,705			145,037	937	1,101,126	2,203,160			(126,445)	5,890
Beginning Balance at Mar. 31, 2021	3,272,928			145,037	937	1,105,137	2,147,436			(133,893)	8,274
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	94,035						94,035
Other comprehensive (loss), net of tax	(2,384)										(2,384)
Common stock dividends and equivalents	(36,342)						(36,342)
Preferred stock dividends		(1,969)						(1,969)
Stock-based compensation	3,468					(3,960)	0			7,428
Exercise of stock options	72					(51)				123
Common shares acquired from stock compensation plan activity	(103)									(103)
Ending Balance at Jun. 30, 2021	3,329,705			145,037	937	1,101,126	2,203,160			(126,445)	5,890
Beginning Balance at Dec. 31, 2021	3,438,325			145,037	937	1,108,594	2,333,288			(126,951)	(22,580)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	165,564						165,564
Other comprehensive (loss), net of tax	(458,752)										(458,752)
Common stock dividends and equivalents	(107,620)						(107,620)
Preferred stock dividends		(3,938)	$ (3,656)					(3,938)	$ (3,656)
Issued in business combination	5,180,124			138,942	891	5,040,291
Stock-based compensation	30,469					419				30,050
Exercise of stock options	497					(451)				948
Common shares acquired from stock compensation plan activity	(21,095)									(21,095)
Common stock repurchase program	(222,130)									(222,130)
Ending Balance at Jun. 30, 2022	7,997,788			283,979	1,828	6,148,853	2,383,638			(339,178)	(481,332)
Beginning Balance at Mar. 31, 2022	8,177,135			283,979	1,828	6,129,440	2,276,875			(239,264)	(275,723)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	182,311						182,311
Other comprehensive (loss), net of tax	(205,609)										(205,609)
Common stock dividends and equivalents	(71,386)						(71,386)
Preferred stock dividends		$ (1,969)	$ (2,193)					$ (1,969)	$ (2,193)
Stock-based compensation	21,466					19,517				1,949
Exercise of stock options	86					(104)				190
Common shares acquired from stock compensation plan activity	(2,128)									(2,128)
Common stock repurchase program	(99,925)									(99,925)
Ending Balance at Jun. 30, 2022	$ 7,997,788			$ 283,979	$ 1,828	$ 6,148,853	$ 2,383,638			$ (339,178)	$ (481,332)