Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period Of Adoption, Adjustment	Cumulative Effect, Period Of Adoption, Adjusted Balance	Performance/Service Based RSAs, RSA,	Board Authorized Purchase Program [Member]	Series C Preferred Stock	Series D Preferred Stock	Series E Preferred Stock	Series F Preferred Stock	Preferred Equity	Preferred Equity Cumulative Effect, Period Of Adoption, Adjusted Balance	Common Stock	Common Stock Cumulative Effect, Period Of Adoption, Adjusted Balance	Surplus	Surplus Cumulative Effect, Period Of Adoption, Adjusted Balance	Retained Earnings	Retained Earnings Cumulative Effect, Period Of Adoption, Adjustment	Retained Earnings Cumulative Effect, Period Of Adoption, Adjusted Balance	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period Of Adoption, Adjusted Balance	Treasury Stock	Treasury Stock Cumulative Effect, Period Of Adoption, Adjusted Balance	Treasury Stock Performance/Service Based RSAs, RSA,	Treasury Stock Board Authorized Purchase Program [Member]
Beginning balance at Dec. 31, 2018	$ 3,780,888									$ 256,716		$ 1,752		$ 1,712,615		$ 2,181,414			$ (124,972)		$ (246,638)
Comprehensive income
Net income	86,686															86,686
Other comprehensive income (loss)	21,597																		21,597
Comprehensive income	108,283
Common stock issued
Stock-based compensation plans, net	7,045													(32,220)		0					39,265
Purchase of treasury stock,				$ (7,468)	$ (29,999)																		$ (7,468)	$ (29,999)
Cash dividends
Common stock ($0.17 per share in 2019 and $0.18 per share in 2020)	(28,183)															(28,183)
Preferred stock(a)	(3,801)															(3,801)
Stock-based compensation expense, net	9,397													9,397
Stockholders' Equity, Other	(293)															(293)
Ending balance at Mar. 31, 2019	3,835,870									256,716		1,752		1,689,792		2,235,824			(103,375)		(244,840)
Cash dividends
Preferred Stock, Dividends, Per Share, Cash Paid						$ 0.3828125	$ 0.3359375	$ 0.3671875
Beginning balance at Dec. 31, 2018	3,780,888									256,716		1,752		1,712,615		2,181,414			(124,972)		(246,638)
Comprehensive income
Net income	171,347
Other comprehensive income (loss)	65,909																		65,909
Comprehensive income	237,256
Ending balance at Jun. 30, 2019	3,899,794									256,716		1,752		1,695,715		2,288,909			(59,063)		(284,235)
Beginning balance at Mar. 31, 2019	3,835,870									256,716		1,752		1,689,792		2,235,824			(103,375)		(244,840)
Comprehensive income
Net income	84,661															84,661
Other comprehensive income (loss)	44,311																		44,311
Comprehensive income	128,972
Common stock issued
Stock-based compensation plans, net	827													(211)		0					1,038
Purchase of treasury stock,				(831)	(39,602)																		(831)	(39,602)
Cash dividends
Common stock ($0.17 per share in 2019 and $0.18 per share in 2020)	(27,776)															(27,776)
Preferred stock(a)	(3,801)															(3,801)
Stock-based compensation expense, net	6,134													6,134
Ending balance at Jun. 30, 2019	3,899,794									256,716		1,752		1,695,715		2,288,909			(59,063)		(284,235)
Cash dividends
Preferred Stock, Dividends, Per Share, Cash Paid						0.3828125	0.3359375	0.3671875
Beginning balance at Dec. 31, 2019	3,922,124		$ 3,823,787							256,716	$ 256,716	1,752	$ 1,752	1,716,431	$ 1,716,431	2,380,867		$ 2,282,530	(33,183)	$ (33,183)	(400,460)	$ (400,460)
Beginning balance (Accounting Standards Update 2016-13) at Dec. 31, 2019		$ (98,337)															$ (98,337)
Comprehensive income
Net income	45,838															45,838
Other comprehensive income (loss)	16,209																		16,209
Comprehensive income	62,046
Common stock issued
Stock-based compensation plans, net	2,896													(20,659)							23,555
Purchase of treasury stock,				(5,555)	$ (71,255)																		(5,555)	$ (71,255)
Cash dividends
Common stock ($0.17 per share in 2019 and $0.18 per share in 2020)	(28,392)															(28,392)
Preferred stock(a)	(3,801)															(3,801)
Stock-based compensation expense, net	10,744													10,744
Ending balance at Mar. 31, 2020	3,790,471									256,716		1,752		1,706,516		2,296,176			(16,974)		(453,714)
Cash dividends
Preferred Stock, Dividends, Per Share, Cash Paid						0.3828125	0.3359375	0.3671875
Beginning balance at Dec. 31, 2019	3,922,124		$ 3,823,787							256,716	$ 256,716	1,752	$ 1,752	1,716,431	$ 1,716,431	2,380,867		$ 2,282,530	(33,183)	$ (33,183)	(400,460)	$ (400,460)
Beginning balance (Accounting Standards Update 2016-13) at Dec. 31, 2019		$ (98,337)															$ (98,337)
Comprehensive income
Net income	194,555
Other comprehensive income (loss)	31,263																		31,263
Comprehensive income	225,818
Ending balance at Jun. 30, 2020	4,024,457									353,846		1,752		1,712,978		2,412,859			(1,920)		(455,057)
Beginning balance at Mar. 31, 2020	3,790,471									256,716		1,752		1,706,516		2,296,176			(16,974)		(453,714)
Comprehensive income
Net income	148,718															148,718
Other comprehensive income (loss)	15,054																		15,054
Comprehensive income	163,772
Common stock issued
Stock-based compensation plans, net	173													1,523							(1,350)
Purchase of treasury stock,				$ 7																			$ 7
Cash dividends
Common stock ($0.17 per share in 2019 and $0.18 per share in 2020)	(27,889)															(27,889)
Preferred stock(a)	(4,144)															(4,144)
Issuance of preferred stock	97,129									97,129
Stock-based compensation expense, net	4,939													4,939
Ending balance at Jun. 30, 2020	$ 4,024,457									$ 353,846		$ 1,752		$ 1,712,978		$ 2,412,859			$ (1,920)		$ (455,057)
Cash dividends
Preferred Stock, Dividends, Per Share, Cash Paid						$ 0.3828125	$ 0.3359375	$ 0.3671875	$ 0.0849931