Other Noninterest Expense - Summary of Other Noninterest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Income and Expenses [Abstract]
Outside processing	$ 12,084	$ 5,052	$ 23,475	$ 15,936
Loan and lease expense	9,323	3,313	15,986	10,430
Professional fees	7,113	5,949	18,026	16,035
Advertising and marketing	7,101	7,674	19,229	22,075
FDIC insurance	6,298	4,376	11,708	12,165
Card processing and issuance costs	5,746	4,090	14,437	12,759
Consumer Financial Protection Bureau and OCC settlement charge	0	0	0	32,000
Other	40,111	25,231	91,920	79,908
Total other noninterest expense	$ 87,776	$ 55,685	$ 194,781	$ 201,308