Parent Company Only Condensed Financial Information - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Adjustments to reconcile net income to net cash used for operating activities:
Gains on equity warrant assets, net		$ (89,142)	$ (54,555)	$ (37,892)	[1]
Amortization of share-based compensation		45,675	36,900	35,494
Other, net		(54,039)	15,909	41,684
Net cash provided by operating activities		933,562	646,865	471,760
Cash flows from investing activities:
Net decrease (increase) in loans		(5,175,409)	(3,170,099)	(3,157,281)
Net cash (used for) provided by investing activities		(4,800,375)	(5,970,496)	981,561
Cash flows from financing activities:
Principal payments of long-term debt		0	(97,781)	0
Proceeds from issuance of common stock, ESPP and ESOP		18,387	27,003	26,147
Common stock repurchase		(147,123)	0	0
Tax effect from stock exercises	[2]	0	0	(3,640)
Net cash provided by (used for) by financing activities		4,515,277	5,700,956	(410,828)
Net increase in cash and cash equivalents		648,464	377,325	1,042,493
Cash and cash equivalents at beginning of period		2,923,075	2,545,750	1,503,257
Cash and cash equivalents at end of period		3,571,539	2,923,075	2,545,750
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net income available to common stockholders		973,840	490,506	382,685
Adjustments to reconcile net income to net cash used for operating activities:
Gains on equity warrant assets, net		(89,142)	(54,555)	(37,892)
Gains on investment securities, net		(13,546)	(17,060)	(3,106)
Distributions of earnings on investments		47,596	14,015	3,137
Net income of subsidiaries		(154,987)	(120,735)	(31,107)
Cash dividends from bank subsidiary		140,000	90,000	40,000
Amortization of share-based compensation		45,675	36,900	35,494
Decrease (increase) in other assets		51,169	12,959	35,699
Increase (decrease) in other liabilities		21,619	11,774	15,293
Other, net		(31,024)	316	2,999
Net cash provided by operating activities		187,334	125,084	82,731
Cash flows from investing activities:
Net decrease (increase) in investment securities from purchases, sales and maturities		73,742	(152,015)	34,055
Net decrease (increase) in loans		0	13,337	(3,478)
Net cash (used for) provided by investing activities		37,127	(143,231)	17,763
Cash flows from financing activities:
Principal payments of long-term debt		0	(51,546)	0
Proceeds from issuance of common stock, ESPP and ESOP		18,387	27,003	26,147
Common stock repurchase		147,123	0	0
Tax effect from stock exercises		0	0	(3,640)
Net cash provided by (used for) by financing activities		(128,736)	(24,543)	22,507
Net increase in cash and cash equivalents		95,725	(42,690)	123,001
Cash and cash equivalents at beginning of period		457,324	500,014	377,013
Cash and cash equivalents at end of period		553,049	457,324	500,014
Bank Subsidiaries | Parent Company
Adjustments to reconcile net income to net cash used for operating activities:
Net income of subsidiaries		(933,641)	(446,769)	(379,629)
Cash flows from investing activities:
Increase (decrease) in investment in subsidiaries		(31,292)	(38,927)	(14,738)
Nonbank Subsidiaries | Parent Company
Adjustments to reconcile net income to net cash used for operating activities:
Net income of subsidiaries		(25,212)	(13,002)	(11,949)
Cash flows from investing activities:
Increase (decrease) in investment in subsidiaries		$ (5,323)	$ 34,374	$ 1,924

[1] Our consolidated statements of income for the year ended December 31, 2016 was modified from prior periods’ presentation to conform to the current period's presentation, which reflects a new line item to separately disclose net gains on equity warrant assets. In prior periods, net gains on equity warrant assets were reported as a component of net gains on derivative instruments. We removed the line item "gains on derivative instruments, net" and reclassified all other gains on derivative instruments, net to other noninterest income.

[2] In 2017 we adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting on a prospective basis with no change to prior period amounts. Note 2—“Summary of Significant Accounting Policies” of the “Notes to the Consolidated Financial Statements” under Part II, Item 8 of this report for additional details.