Loans and Allowance for Credit Losses for Loans - Summary of Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ 309,614	$ 155,105	$ 161,759	$ 151,859
Loans charged-off	(17,125)	(2,987)	(40,087)	(14,137)
Charged-off loans recovered	1,710	978	5,120	3,812
Net charge-offs	(15,415)	(2,009)	(34,967)	(10,325)
Provision for loan losses	30,833	8,757	105,709	20,319
Ending balance	325,032	161,853	325,032	161,853
Allowance for PCD loans reclassification			61,600
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			92,531
Commercial and Industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	132,039	94,384	104,059	90,956
Loans charged-off	(13,965)	(527)	(31,349)	(7,882)
Charged-off loans recovered	428	330	1,796	2,008
Net charge-offs	(13,537)	(197)	(29,553)	(5,874)
Provision for loan losses	11,907	6,815	40,734	15,920
Ending balance	130,409	101,002	130,409	101,002
Commercial and Industrial | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			15,169
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	131,702	48,978	45,673	49,650
Loans charged-off	(695)	(158)	(766)	(158)
Charged-off loans recovered	100	28	244	71
Net charge-offs	(595)	(130)	(522)	(87)
Provision for loan losses	13,543	(77)	49,702	(792)
Ending balance	144,650	48,771	144,650	48,771
Commercial Real Estate | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			49,797
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	29,630	5,219	5,060	5,041
Loans charged-off	(7)	(111)	(348)	(126)
Charged-off loans recovered	31	3	626	13
Net charge-offs	24	(108)	278	(113)
Provision for loan losses	(1,040)	191	2,701	374
Ending balance	28,614	5,302	28,614	5,302
Residential Mortgage | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			20,575
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	16,243	6,524	6,967	6,212
Loans charged-off	(2,458)	(2,191)	(7,624)	(5,971)
Charged-off loans recovered	1,151	617	2,454	1,720
Net charge-offs	(1,307)	(1,574)	(5,170)	(4,251)
Provision for loan losses	6,423	1,828	12,572	4,817
Ending balance	$ 21,359	$ 6,778	21,359	$ 6,778
Consumer | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			$ 6,990