Loans and Allowance for Credit Losses for Loans - Summary of Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ 283,342	$ 154,381	$ 161,759	$ 151,859
Loans charged-off	(16,657)	(4,825)	(22,962)	(11,150)
Charged-off loans recovered	1,904	1,843	3,410	2,834
Net (charge-offs) recoveries	(14,753)	(2,982)	(19,552)	(8,316)
Provision for loan losses	41,025	3,706	74,876	11,562
Ending balance	309,614	155,105	309,614	155,105
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	127,437	94,630	104,059	90,956
Loans charged-off	(14,024)	(3,073)	(17,384)	(7,355)
Charged-off loans recovered	799	1,195	1,368	1,678
Net (charge-offs) recoveries	(13,225)	(1,878)	(16,016)	(5,677)
Provision for loan losses	17,827	1,632	28,827	9,105
Ending balance	132,039	94,384	132,039	94,384
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	111,585	47,762	45,673	49,650
Loans charged-off	(27)	0	(71)	0
Charged-off loans recovered	51	22	144	43
Net (charge-offs) recoveries	24	22	73	43
Provision for loan losses	20,093	1,194	36,159	(715)
Ending balance	131,702	48,978	131,702	48,978
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	29,456	5,139	5,060	5,041
Loans charged-off	(5)	0	(341)	(15)
Charged-off loans recovered	545	9	595	10
Net (charge-offs) recoveries	540	9	254	(5)
Provision for loan losses	(366)	71	3,741	183
Ending balance	29,630	5,219	29,630	5,219
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	14,864	6,850	6,967	6,212
Loans charged-off	(2,601)	(1,752)	(5,166)	(3,780)
Charged-off loans recovered	509	617	1,303	1,103
Net (charge-offs) recoveries	(2,092)	(1,135)	(3,863)	(2,677)
Provision for loan losses	3,471	809	6,149	2,989
Ending balance	$ 16,243	$ 6,524	16,243	$ 6,524
Consumer | Cumulative Effect, Period Of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance			$ 6,990