CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Series A	Preferred Series B	Common Stock	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Preferred Stock	Preferred Stock 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 Preferred Series A	Retained Earnings Preferred Series B	Retained Earnings Common Stock	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Cumulative Effect, Period of Adoption, Adjusted Balance	Treasury Stock	Treasury Stock Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	$ 3,350,454					$ 3,353,422	$ 209,691	$ 209,691	$ 116,240	$ 116,240	$ 2,796,499	$ 2,796,499	$ 299,642					$ 302,610	$ (69,431)	$ (69,431)	$ (2,187)	$ (2,187)
Adjustment due to adoption of ASUs | ASU 2016-02					$ 4,414												$ 4,414
Adjustment due to adoption of ASUs | ASU 2017-08					(1,446)												(1,446)
Adjusted balance due to adoption of ASUs	3,350,454					3,353,422	209,691	209,691	116,240	116,240	2,796,499	2,796,499	299,642					302,610	(69,431)	(69,431)	(2,187)	(2,187)
Adjusted balance due to adoption of ASUs | ASU 2016-02					4,414												4,414
Adjusted balance due to adoption of ASUs | ASU 2017-08					(1,446)												(1,446)
Beginning balance at Dec. 31, 2018	3,350,454					3,353,422	209,691	209,691	$ 116,240	116,240	2,796,499	2,796,499	299,642					302,610	(69,431)	(69,431)	(2,187)	(2,187)
Beginning balance (ASU 2016-02) at Dec. 31, 2018					4,414												4,414
Beginning balance (ASU 2017-08) at Dec. 31, 2018					(1,446)												(1,446)
Beginning balance (in shares) at Dec. 31, 2018									331,431
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	3,444,879					3,353,422	209,691	209,691	$ 116,466	116,240	2,799,434	2,796,499	375,983					302,610	(53,257)	(69,431)	(3,438)	(2,187)
Adjustment due to adoption of ASUs | ASU 2016-02					4,414												4,414
Adjustment due to adoption of ASUs | ASU 2017-08					(1,446)												(1,446)
Adjusted balance due to adoption of ASUs	3,444,879					3,353,422	209,691	209,691	$ 116,466	116,240	2,799,434	2,796,499	375,983					302,610	(53,257)	(69,431)	(3,438)	(2,187)
Adjusted balance due to adoption of ASUs | ASU 2016-02					4,414												4,414
Adjusted balance due to adoption of ASUs | ASU 2017-08					(1,446)												(1,446)
Net income	113,330												113,330
Other comprehensive income, net of tax	16,174																		16,174
Cash dividends declared:
Cash dividends declared on preferred stock		$ (1,797)	$ (1,375)											$ (1,797)	$ (1,375)
Cash dividends declared on common stock				$ (36,686)												$ (36,686)
Effect of stock incentive plan, net (in shares)									302
Effect of stock incentive plan, net	1,811								$ 226		2,935		(99)								(1,251)
Ending balance at Mar. 31, 2019	3,444,879						209,691		$ 116,466		2,799,434		375,983						(53,257)		(3,438)
Ending balance (in shares) at Mar. 31, 2019									331,733
Beginning balance at Dec. 31, 2018	3,350,454					3,353,422	209,691	209,691	$ 116,240	116,240	2,796,499	2,796,499	299,642					302,610	(69,431)	(69,431)	(2,187)	(2,187)
Beginning balance (ASU 2016-02) at Dec. 31, 2018					4,414												4,414
Beginning balance (ASU 2017-08) at Dec. 31, 2018					(1,446)												(1,446)
Beginning balance (in shares) at Dec. 31, 2018									331,431
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	3,558,075					3,353,422	209,691	209,691	$ 116,650	116,240	2,807,266	2,796,499	454,020					302,610	(26,468)	(69,431)	(3,084)	(2,187)
Adjustment due to adoption of ASUs | ASU 2016-02					4,414												4,414
Adjustment due to adoption of ASUs | ASU 2017-08					(1,446)												(1,446)
Adjusted balance due to adoption of ASUs	3,558,075					3,353,422	209,691	209,691	116,650	116,240	2,807,266	2,796,499	454,020					302,610	(26,468)	(69,431)	(3,084)	(2,187)
Adjusted balance due to adoption of ASUs | ASU 2016-02					4,414												4,414
Adjusted balance due to adoption of ASUs | ASU 2017-08					(1,446)												(1,446)
Net income	271,689
Ending balance at Sep. 30, 2019	3,558,075						209,691		$ 116,650		2,807,266		454,020						(26,468)		(3,084)
Ending balance (in shares) at Sep. 30, 2019									331,806
Beginning balance at Dec. 31, 2018	3,350,454					3,353,422	209,691	209,691	$ 116,240	116,240	2,796,499	2,796,499	299,642					302,610	(69,431)	(69,431)	(2,187)	(2,187)
Beginning balance (ASU 2016-02) at Dec. 31, 2018					4,414												4,414
Beginning balance (ASU 2017-08) at Dec. 31, 2018					(1,446)												(1,446)
Beginning balance (in shares) at Dec. 31, 2018									331,431
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	3,350,454				(28,187)	3,353,422	209,691	209,691	$ 116,240	116,240	2,796,499	2,796,499	299,642				(28,187)	302,610	(69,431)	(69,431)	(2,187)	(2,187)
Adjustment due to adoption of ASUs | ASU 2016-02					4,414												4,414
Adjustment due to adoption of ASUs | ASU 2017-08					(1,446)												(1,446)
Adjusted balance due to adoption of ASUs	3,350,454				(28,187)	3,353,422	209,691	209,691	116,240	116,240	2,796,499	2,796,499	299,642				(28,187)	302,610	(69,431)	(69,431)	(2,187)	(2,187)
Adjusted balance due to adoption of ASUs | ASU 2016-02					4,414												4,414
Adjusted balance due to adoption of ASUs | ASU 2017-08					(1,446)												(1,446)
Ending balance at Dec. 31, 2019	$ 4,384,188				(28,187)	4,356,001	209,691	209,691	$ 141,423	141,423	3,622,208	3,622,208	443,559				(28,187)	415,372	(32,214)	(32,214)	(479)	(479)
Ending balance (in shares) at Dec. 31, 2019									403,278
Cash dividends declared:
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Adjustment due to adoption of ASUs	$ 3,444,879						209,691		$ 116,466		2,799,434		375,983						(53,257)		(3,438)
Adjusted balance due to adoption of ASUs	3,444,879						209,691		116,466		2,799,434		375,983						(53,257)		(3,438)
Beginning balance at Mar. 31, 2019	3,444,879						209,691		$ 116,466		2,799,434		375,983						(53,257)		(3,438)
Beginning balance (in shares) at Mar. 31, 2019									331,733
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	3,504,118						209,691		$ 116,571		2,804,059		412,190						(35,131)		(3,262)
Adjusted balance due to adoption of ASUs	3,504,118						209,691		$ 116,571		2,804,059		412,190						(35,131)		(3,262)
Net income	76,468												76,468
Other comprehensive income, net of tax	18,126																		18,126
Cash dividends declared:
Cash dividends declared on preferred stock		(1,797)	(1,375)											(1,797)	(1,375)
Cash dividends declared on common stock				(36,712)												(36,712)
Effect of stock incentive plan, net (in shares)									55
Effect of stock incentive plan, net	4,529								$ 105		4,625		(377)								176
Ending balance at Jun. 30, 2019	3,504,118						209,691		$ 116,571		2,804,059		412,190						(35,131)		(3,262)
Ending balance (in shares) at Jun. 30, 2019									331,788
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	3,504,118						209,691		$ 116,571		2,804,059		412,190						(35,131)		(3,262)
Adjusted balance due to adoption of ASUs	3,504,118						209,691		116,571		2,804,059		412,190						(35,131)		(3,262)
Adjustment due to adoption of ASUs	3,558,075						209,691		116,650		2,807,266		454,020						(26,468)		(3,084)
Adjusted balance due to adoption of ASUs	3,558,075						209,691		$ 116,650		2,807,266		454,020						(26,468)		(3,084)
Net income	81,891												81,891
Other comprehensive income, net of tax	8,663																		8,663
Cash dividends declared:
Cash dividends declared on preferred stock		(1,797)	(1,375)											(1,797)	(1,375)
Cash dividends declared on common stock				(36,732)												(36,732)
Effect of stock incentive plan, net (in shares)									18
Effect of stock incentive plan, net	3,307								$ 79		3,207		(157)								178
Ending balance at Sep. 30, 2019	3,558,075						209,691		$ 116,650		2,807,266		454,020						(26,468)		(3,084)
Ending balance (in shares) at Sep. 30, 2019									331,806
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	3,558,075						209,691		$ 116,650		2,807,266		454,020						(26,468)		(3,084)
Adjusted balance due to adoption of ASUs	3,558,075						209,691		116,650		2,807,266		454,020						(26,468)		(3,084)
Adjustment due to adoption of ASUs	4,384,188				(28,187)	4,356,001	209,691	209,691	141,423	141,423	3,622,208	3,622,208	443,559				(28,187)	415,372	(32,214)	(32,214)	(479)	(479)
Adjusted balance due to adoption of ASUs	4,384,188				(28,187)	4,356,001	209,691	209,691	141,423	141,423	3,622,208	3,622,208	443,559				(28,187)	415,372	(32,214)	(32,214)	(479)	(479)
Beginning balance at Dec. 31, 2019	4,384,188				(28,187)	4,356,001	209,691	209,691	$ 141,423	141,423	3,622,208	3,622,208	443,559				(28,187)	415,372	(32,214)	(32,214)	(479)	(479)
Beginning balance (in shares) at Dec. 31, 2019									403,278
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	4,420,998				(28,187)	4,356,001	209,691	209,691	$ 141,613	141,423	3,624,036	3,622,208	452,424				(28,187)	415,372	(6,566)	(32,214)	(200)	(479)
Adjusted balance due to adoption of ASUs	4,420,998				(28,187)	4,356,001	209,691	209,691	$ 141,613	141,423	3,624,036	3,622,208	452,424				(28,187)	415,372	(6,566)	(32,214)	(200)	(479)
Net income	87,268												87,268
Other comprehensive income, net of tax	25,648																		25,648
Cash dividends declared:
Cash dividends declared on preferred stock		(1,797)	(1,375)											(1,797)	(1,375)
Cash dividends declared on common stock				(44,979)												(44,979)
Effect of stock incentive plan, net (in shares)									466
Effect of stock incentive plan, net	232								$ 190		1,828		(2,065)								279
Ending balance at Mar. 31, 2020	4,420,998						209,691		$ 141,613		3,624,036		452,424						(6,566)		(200)
Ending balance (in shares) at Mar. 31, 2020									403,744
Beginning balance at Dec. 31, 2019	4,384,188				(28,187)	4,356,001	209,691	209,691	$ 141,423	141,423	3,622,208	3,622,208	443,559				(28,187)	415,372	(32,214)	(32,214)	(479)	(479)
Beginning balance (in shares) at Dec. 31, 2019									403,278
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	4,384,188				(28,187)	4,356,001	209,691	209,691	$ 141,718	141,423	3,633,321	3,622,208	553,826				(28,187)	415,372	(4,783)	(32,214)	(10)	(479)
Adjusted balance due to adoption of ASUs	4,384,188				$ (28,187)	$ 4,356,001	209,691	$ 209,691	141,718	$ 141,423	3,633,321	$ 3,622,208	553,826				$ (28,187)	$ 415,372	(4,783)	$ (32,214)	(10)	$ (479)
Net income	285,243
Ending balance at Sep. 30, 2020	4,533,763						209,691		$ 141,718		3,633,321		553,826						(4,783)		(10)
Ending balance (in shares) at Sep. 30, 2020									403,879
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	4,420,998						209,691		$ 141,613		3,624,036		452,424						(6,566)		(200)
Adjusted balance due to adoption of ASUs	4,420,998						209,691		141,613		3,624,036		452,424						(6,566)		(200)
Beginning balance at Mar. 31, 2020	4,420,998						209,691		$ 141,613		3,624,036		452,424						(6,566)		(200)
Beginning balance (in shares) at Mar. 31, 2020									403,744
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	4,474,488						209,691		$ 141,667		3,628,792		499,511						(4,938)		(235)
Adjusted balance due to adoption of ASUs	4,474,488						209,691		$ 141,667		3,628,792		499,511						(4,938)		(235)
Net income	95,601												95,601
Other comprehensive income, net of tax	1,628																		1,628
Cash dividends declared:
Cash dividends declared on preferred stock		(1,797)	(1,375)											(1,797)	(1,375)
Cash dividends declared on common stock				(44,750)												(44,750)
Effect of stock incentive plan, net (in shares)									52
Effect of stock incentive plan, net	4,183								$ 54		4,756		(592)								(35)
Ending balance at Jun. 30, 2020	4,474,488						209,691		$ 141,667		3,628,792		499,511						(4,938)		(235)
Ending balance (in shares) at Jun. 30, 2020									403,796
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	4,474,488						209,691		$ 141,667		3,628,792		499,511						(4,938)		(235)
Adjusted balance due to adoption of ASUs	4,474,488						209,691		141,667		3,628,792		499,511						(4,938)		(235)
Adjustment due to adoption of ASUs	4,474,488						209,691		141,718		3,633,321		553,826						(4,783)		(10)
Adjusted balance due to adoption of ASUs	4,474,488						209,691		$ 141,718		3,633,321		553,826						(4,783)		(10)
Net income	102,374												102,374
Other comprehensive income, net of tax	155																		155
Cash dividends declared:
Cash dividends declared on preferred stock		$ (1,797)	$ (1,375)											$ (1,797)	$ (1,375)
Cash dividends declared on common stock				$ (44,770)												$ (44,770)
Effect of stock incentive plan, net (in shares)									83
Effect of stock incentive plan, net	4,688								$ 51		4,529		(117)								225
Ending balance at Sep. 30, 2020	4,533,763						209,691		$ 141,718		3,633,321		553,826						(4,783)		(10)
Ending balance (in shares) at Sep. 30, 2020									403,879
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASUs	4,533,763						209,691		$ 141,718		3,633,321		553,826						(4,783)		(10)
Adjusted balance due to adoption of ASUs	$ 4,533,763						$ 209,691		$ 141,718		$ 3,633,321		$ 553,826						$ (4,783)		$ (10)