Loans and Allowance for Credit Losses for Loans - Summary of Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Allowance for loan losses:
Beginning balance	$ 340,243	$ 161,759
Loans charged-off	(8,800)	(6,305)
Charged-off loans recovered	2,745	1,506
Net (charge-offs) recoveries	(6,055)	(4,799)
Provision for loan losses	8,692	33,851
Ending balance	342,880	283,342
Allowance for PCD loans reclassification		61,600
Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses:
Beginning balance		92,531
Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses:
Beginning balance		254,290
Commercial and industrial
Allowance for loan losses:
Beginning balance	131,070	104,059
Loans charged-off	(7,142)	(3,360)
Charged-off loans recovered	1,589	569
Net (charge-offs) recoveries	(5,553)	(2,791)
Provision for loan losses	891	11,000
Ending balance	126,408	127,437
Commercial and industrial \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses:
Beginning balance		15,169
Commercial and industrial \| Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses:
Beginning balance		119,228
Commercial Real Estate
Allowance for loan losses:
Beginning balance	164,113	45,673
Loans charged-off	(382)	(44)
Charged-off loans recovered	69	93
Net (charge-offs) recoveries	(313)	49
Provision for loan losses	10,436	16,066
Ending balance	174,236	111,585
Commercial Real Estate \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses:
Beginning balance		49,797
Commercial Real Estate \| Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses:
Beginning balance		95,470
Residential Mortgage
Allowance for loan losses:
Beginning balance	28,873	5,060
Loans charged-off	(138)	(336)
Charged-off loans recovered	157	50
Net (charge-offs) recoveries	19	(286)
Provision for loan losses	(1,720)	4,107
Ending balance	27,172	29,456
Residential Mortgage \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses:
Beginning balance		20,575
Residential Mortgage \| Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses:
Beginning balance		25,635
Consumer
Allowance for loan losses:
Beginning balance	16,187	6,967
Loans charged-off	(1,138)	(2,565)
Charged-off loans recovered	930	794
Net (charge-offs) recoveries	(208)	(1,771)
Provision for loan losses	(915)	2,678
Ending balance	$ 15,064	14,864
Consumer \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses:
Beginning balance		6,990
Consumer \| Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses:
Beginning balance		$ 13,957

Amount of increase in allowance for credit loss on financing receivable purchased with credit deterioration.

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Amount, after recovery, of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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