Parent Company Only Financial Statements Parent Company Only Financial Statements, Condensed Cash Flow Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows From Operating Activities: [Abstract]
Net income	$ 435,071	$ 500,685	$ 446,424
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Change in other assets	1,739	18,955	27,507
Change in other liabilities	8,895	92,463	(144,537)
Net cash provided by operating activities	(416,256)	(473,679)	(552,006)
Cash Flows From Investing Activities: [Abstract]
Acquisitions, net of cash acquired	0	0	(175,755)
Net cash used in investing activities	(2,458,835)	(2,323,737)	(1,807,631)
Cash Flows From Financing Activities: [Abstract]
Issuance of common and treasury stock, net	(4,933)	(7)	(88)
Dividends paid	(144,437)	(143,496)	(127,188)
Repurchase of common stock	(75,830)	(129,483)	(53,465)
Net cash used in financing activities	2,796,843	2,912,813	1,186,007
Net increase (decrease) in cash and cash equivalents	(78,248)	115,397	(1,173,630)
Cash and cash equivalents at beginning of period	1,258,821	1,143,424	2,317,054
Cash and cash equivalents at end of period	1,180,573	1,258,821	1,143,424
Cash paid for interest	160,288	417,070	243,121
Parent Company [Member]
Cash Flows From Operating Activities: [Abstract]
Net income	435,030	500,758	445,646
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Equity in undistributed income of bank subsidiaries	(276,217)	(166,797)	(37,515)
Equity in undistributed income of non-bank subsidiaries	35,610	10,768	12,914
Change in other assets	(13,760)	5,075	1,072
Change in other liabilities	850	855	(13,434)
Net cash provided by operating activities	209,033	340,509	406,539
Cash Flows From Investing Activities: [Abstract]
Investment in subsidiaries	(14,807)	(19,837)	(31,901)
Acquisitions, net of cash acquired	0	0	(232,680)
Net cash used in investing activities	(14,807)	(19,837)	(264,581)
Cash Flows From Financing Activities: [Abstract]
Issuance of common and treasury stock, net	(4,933)	(7)	(88)
Dividends paid	144,437	143,496	127,188
Repurchase of common stock	75,830	129,483	53,465
Net cash used in financing activities	(225,200)	(272,986)	(180,741)
Net increase (decrease) in cash and cash equivalents	(30,974)	47,686	(38,783)
Cash and cash equivalents at beginning of period	214,779	167,093	205,876
Cash and cash equivalents at end of period	183,805	214,779	167,093
Cash paid for interest	$ 14,064	$ 15,099	$ 11,457