Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period Of Adoption, Adjustment	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, Adjustment	Common Stock	Common Stock Cumulative Effect, Period Of Adoption, Adjustment	Surplus	Surplus Cumulative Effect, Period Of Adoption, Adjustment	Retained Earnings	Retained Earnings Cumulative Effect, Period Of Adoption, Adjustment	Retained Earnings Series F Preferred Stock	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period Of Adoption, Adjustment	Treasury Stock	Treasury Stock Cumulative Effect, Period Of Adoption, Adjustment	Treasury Stock Performance/Service Based RSAs, RSA,	Treasury Stock Board Authorized Purchase Program [Member]
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)
Comprehensive income
Net income	45,838														45,838
Other comprehensive income (loss)	16,209																	16,209
Comprehensive income	62,046
Common stock issued
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	2,896												(20,659)		0					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)
Comprehensive income
Net income	194,555														194,555
Other comprehensive income (loss)	31,263																	31,263
Comprehensive income	225,818
Cash dividends
Proceeds from issuance of preferred shares	97,129
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
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	173												1,523		0					(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)
Proceeds from issuance of preferred shares	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
Beginning balance at Dec. 31, 2020	4,090,933								353,512		1,752		1,720,329		2,458,920			12,618		(456,198)
Comprehensive income
Net income	94,301														94,301
Other comprehensive income (loss)	(16,811)																	(16,811)
Comprehensive income	77,490
Common stock issued
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	10,556												(16,986)							27,542
Purchase of treasury stock,			(3,593)	(17,973)																		(3,593)	(17,973)
Cash dividends
Common stock ($0.17 per share in 2019 and $0.18 per share in 2020)	(27,870)														(27,870)
Preferred stock(a)	(5,207)														(5,207)
Stock-based compensation expense, net	3,444												3,444
Ending balance at Mar. 31, 2021	4,127,780								353,512		1,752		1,706,786		2,520,144			(4,193)		(450,222)
Cash dividends
Preferred Stock, Dividends, Per Share, Cash Paid					0.3828125	0.3359375	0.3671875										$ 0.3515625
Beginning balance at Dec. 31, 2020	4,090,933								353,512		1,752		1,720,329		2,458,920			12,618		(456,198)
Comprehensive income
Net income	185,307														185,307
Other comprehensive income (loss)	(9,729)																	(9,729)
Comprehensive income	175,578
Cash dividends
Proceeds from issuance of preferred shares	0
Ending balance at Jun. 30, 2021	4,110,052								290,200		1,752		1,708,246		2,576,766			2,889		(469,801)
Beginning balance at Mar. 31, 2021	4,127,780								353,512		1,752		1,706,786		2,520,144			(4,193)		(450,222)
Comprehensive income
Net income	91,007														91,007
Other comprehensive income (loss)	7,082																	7,082
Comprehensive income	98,088
Common stock issued
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	7,618												(3,632)							11,250
Purchase of treasury stock,			$ (856)	$ (29,972)																		$ (856)	$ 29,972
Cash dividends
Common stock ($0.17 per share in 2019 and $0.18 per share in 2020)	(27,822)														(27,822)
Preferred stock(a)	(4,875)														(4,875)
Stock-based compensation expense, net	5,092												5,092
Ending balance at Jun. 30, 2021	4,110,052								290,200		$ 1,752		$ 1,708,246		2,576,766			$ 2,889		$ (469,801)
Cash dividends
Preferred Stock, Dividends, Per Share, Cash Paid					$ 0.3197115	$ 0.3359375	$ 0.3671875	$ 0.3515625
Preferred Stock, Redemption Amount	$ (65,000)								$ 63,313						$ 1,687