Parent Company Only Condensed Financial Information - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Adjustments to reconcile net income to net cash used for operating activities:
Gains on investment securities, net	$ (420,752)	$ (134,670)	$ (88,094)
Gains on derivatives, net	(237,428)	(138,078)	(89,142)
Amortization of share-based compensation	83,986	66,815	45,675
Other, net	(287,905)	(74,240)	(54,039)
Net cash provided by operating activities	1,445,487	1,164,129	933,562
Cash flows from investing activities:
Net decrease (increase) in loans	(11,926,436)	(4,773,775)	(5,175,409)
Business acquisitions	26,700	102,328	0
Net cash used for investing activities	(31,205,721)	(9,371,882)	(4,800,375)
Cash flows from financing activities:
Principal payments of long-term debt	0	(358,395)	0
Proceeds from issuance of common stock, ESPP and ESOP	31,146	24,818	18,387
Net proceeds from the issuance of preferred stock	0	340,138	0
Payment of preferred stock dividends	(17,151)	0	0
Common stock repurchase	(60,020)	(352,511)	(147,123)
Net cash provided by financing activities	40,653,214	11,417,997	4,515,277
Net increase in cash and cash equivalents	10,892,980	3,210,244	648,464
Cash and cash equivalents at beginning of period	6,781,783	3,571,539	2,923,075
Cash and cash equivalents at end of period	17,674,763	6,781,783	3,571,539
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net income before preferred stock dividend	1,208,368	1,136,856	973,840
Adjustments to reconcile net income to net cash used for operating activities:
Gains on equity warrant assets, net	(30,018)	0	0
Gains on investment securities, net	(157,594)	(45,345)	(13,546)
Gains on derivatives, net	(226,942)	(138,078)	(89,142)
Distributions of earnings from investment securities	65,237	49,776	47,596
Net income of subsidiaries	(211,213)	(775,867)	(154,987)
Cash dividends from bank subsidiary	50,000	733,000	140,000
Amortization of share-based compensation	83,986	66,815	45,675
Decrease in other assets	17,189	27,205	51,169
Increase in other liabilities	98,209	21,391	21,619
Other, net	13,206	8,084	(31,024)
Net cash provided by operating activities	74,486	765,715	187,334
Cash flows from investing activities:
Net decrease in investment securities from purchases, sales and maturities	122,823	128,635	73,742
Net decrease (increase) in loans	14,563	(15,245)	0
Net cash used for investing activities	(653,673)	(171,888)	37,127
Cash flows from financing activities:
Principal payments of long-term debt	0	(358,395)	0
Proceeds from issuance of 3.125% Senior Notes	495,024	0	0
Proceeds from issuance of common stock, ESPP and ESOP	31,146	24,818	18,387
Net proceeds from the issuance of preferred stock	0	340,138	0
Payment of preferred stock dividends		0	0
Common stock repurchase	(60,020)	(352,511)	(147,123)
Net cash provided by financing activities	448,999	(345,950)	(128,736)
Net increase in cash and cash equivalents	(130,188)	247,877	95,725
Cash and cash equivalents at beginning of period	800,926	553,049	457,324
Cash and cash equivalents at end of period	670,738	800,926	553,049
Bank Subsidiary | Parent Company
Adjustments to reconcile net income to net cash used for operating activities:
Net income of subsidiaries	(826,243)	(1,036,618)	(933,641)
Cash flows from investing activities:
Increase (decrease) in investment in subsidiaries	(68,630)	(42,952)	(31,292)
Capital Infusion In Bank Subsidiary	(700,000)	0	0
Nonbank Subsidiaries | Parent Company
Adjustments to reconcile net income to net cash used for operating activities:
Net income of subsidiaries	(220,912)	(57,371)	(25,212)
Cash flows from investing activities:
Increase (decrease) in investment in subsidiaries	4,271	23,275	(5,323)
Business acquisitions	$ 26,700	$ 265,601	$ 0