Parent Company Only Condensed Financial Information - Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Income Statements, Captions [Line Items]
Interest income	$ 607,558	$ 543,127	$ 523,523	$ 567,402	$ 588,735	$ 583,892	$ 585,767	$ 551,014	$ 2,241,610	$ 2,309,408	$ 1,969,909
Interest expense	(16,078)	(15,387)	(10,596)	(43,265)	(55,067)	(63,248)	(56,364)	(38,128)	(85,326)	(212,807)	(75,921)
Gains on equity warrant assets, net									237,428	138,078	89,142
Gains on investment securities, net									420,752	134,670	88,094
Income tax expense	(148,096)	(162,265)	(87,869)	(49,357)	(94,061)	(105,075)	(119,114)	(107,435)	(447,587)	(425,685)	(351,561)
Preferred stock dividends	(4,594)	(4,594)	(4,594)	(3,369)					(17,151)	0	0
Net income available to common stockholders	$ 388,316	$ 441,713	$ 228,935	$ 132,253	$ 262,856	$ 267,281	$ 317,987	$ 288,732	1,191,217	1,136,856	973,840
Parent Company
Condensed Income Statements, Captions [Line Items]
Interest income									2,849	4,473	3,307
Interest expense									(21,565)	(31,666)	(32,037)
Dividend income from bank subsidiary									50,000	733,000	140,000
Gains on equity warrant assets, net									226,942	138,078	89,142
Gains on investment securities, net									157,594	45,345	13,546
Fund management fees and other noninterest income									62,046	21,567	26,388
General and administrative expenses									(120,863)	(94,712)	(70,976)
Income tax expense									(145,790)	(40,218)	(14,383)
Income before net income of subsidiaries									211,213	775,867	154,987
Net income before preferred stock dividend									1,208,368	1,136,856	973,840
Preferred stock dividends									(17,151)	0	0
Net income available to common stockholders									1,191,217	1,136,856	973,840
Parent Company | Bank Subsidiary
Condensed Income Statements, Captions [Line Items]
Income before net income of subsidiaries									826,243	1,036,618	933,641
Equity in undistributed net income of subsidiaries									776,243	303,618	793,641
Parent Company | Nonbank Subsidiaries
Condensed Income Statements, Captions [Line Items]
Income before net income of subsidiaries									220,912	57,371	25,212
Equity in undistributed net income of subsidiaries									$ 220,912	$ 57,371	$ 25,212