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	297,826						297,826
Other comprehensive (loss), net of tax	(40,748)										(40,748)
Common stock dividends and equivalents	(108,882)						(108,882)
Preferred stock dividends		$ (5,906)						$ (5,906)
Stock-based compensation	10,076					508				9,568
Exercise of stock options	3,469					(5,155)				8,624
Common shares acquired from stock compensation plan activity	(4,271)									(4,271)
Ending Balance at Sep. 30, 2021	3,386,189			145,037	937	1,104,885	2,260,560			(126,738)	1,508
Beginning Balance at Jun. 30, 2021	3,329,705			145,037	937	1,101,126	2,203,160			(126,445)	5,890
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	95,713						95,713
Other comprehensive (loss), net of tax	(4,382)										(4,382)
Common stock dividends and equivalents	(36,345)						(36,345)
Preferred stock dividends		(1,968)						(1,968)
Stock-based compensation	3,643					3,819	0			(176)
Exercise of stock options	83					(60)				143
Common shares acquired from stock compensation plan activity	(260)									(260)
Ending Balance at Sep. 30, 2021	3,386,189			145,037	937	1,104,885	2,260,560			(126,738)	1,508
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	399,532						399,532
Other comprehensive (loss), net of tax	(714,321)										(714,321)
Common stock dividends and equivalents	(178,049)						(178,049)
Preferred stock dividends		(5,906)	$ (5,850)					(5,906)	$ (5,850)
Common stock contribution to charitable foundation	10,500					(1,701)				12,201
Issued in business combination	5,180,124			138,942	891	5,040,291
Stock-based compensation	43,231					14,726				28,505
Exercise of stock options	635					(613)				1,248
Common shares acquired from stock compensation plan activity	(22,545)									(22,545)
Common stock repurchase program	(319,266)									(319,266)
Ending Balance at Sep. 30, 2022	7,826,410			283,979	1,828	6,161,297	2,543,015			(426,808)	(736,901)
Beginning Balance at Jun. 30, 2022	7,997,788			283,979	1,828	6,148,853	2,383,638			(339,178)	(481,332)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	233,968						233,968
Other comprehensive (loss), net of tax	(255,569)										(255,569)
Common stock dividends and equivalents	(70,429)						(70,429)
Preferred stock dividends		$ (1,968)	$ (2,194)					$ (1,968)	$ (2,194)
Common stock contribution to charitable foundation	10,500					(1,701)				12,201
Stock-based compensation	12,762					14,307				(1,545)
Exercise of stock options	138					(162)				300
Common shares acquired from stock compensation plan activity	(1,450)									(1,450)
Common stock repurchase program	(97,136)									(97,136)
Ending Balance at Sep. 30, 2022	$ 7,826,410			$ 283,979	$ 1,828	$ 6,161,297	$ 2,543,015			$ (426,808)	$ (736,901)