Loans and Allowance for Credit Losses for Loans - Summary of Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 161,759	$ 151,859
Loans charged-off	(45,289)	(22,215)
Charged-off loans recovered	7,320	6,306
Net (charge-offs) recoveries	(37,969)	(15,909)
Provision for loan losses	123,922	25,809	$ 31,661
Ending balance	340,243	161,759	151,859
Allowance for PCD loans reclassification	61,600
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	92,531
Ending balance		92,531
Cumulative Effect, Period of Adoption, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	254,290
Ending balance		254,290
Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	104,059	90,956
Loans charged-off	(34,630)	(13,260)
Charged-off loans recovered	1,956	2,397
Net (charge-offs) recoveries	(32,674)	(10,863)
Provision for loan losses	44,516	23,966
Ending balance	131,070	104,059	90,956
Commercial and industrial \| Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	15,169
Ending balance		15,169
Commercial and industrial \| Cumulative Effect, Period of Adoption, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	119,228
Ending balance		119,228
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	45,673	49,650
Loans charged-off	(767)	(158)
Charged-off loans recovered	1,506	1,237
Net (charge-offs) recoveries	739	1,079
Provision for loan losses	67,904	(5,056)
Ending balance	164,113	45,673	49,650
Commercial real estate \| Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	49,797
Ending balance		49,797
Commercial real estate \| Cumulative Effect, Period of Adoption, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	95,470
Ending balance		95,470
Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5,060	5,041
Loans charged-off	(598)	(126)
Charged-off loans recovered	670	66
Net (charge-offs) recoveries	72	(60)
Provision for loan losses	3,166	79
Ending balance	28,873	5,060	5,041
Residential mortgage \| Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	20,575
Ending balance		20,575
Residential mortgage \| Cumulative Effect, Period of Adoption, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	25,635
Ending balance		25,635
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	6,967	6,212
Loans charged-off	(9,294)	(8,671)
Charged-off loans recovered	3,188	2,606
Net (charge-offs) recoveries	(6,106)	(6,065)
Provision for loan losses	8,336	6,820
Ending balance	16,187	6,967	$ 6,212
Consumer \| Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	6,990
Ending balance		6,990
Consumer \| Cumulative Effect, Period of Adoption, Adjusted Balance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 13,957
Ending balance		$ 13,957

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

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- Definition

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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Amount of increase in allowance for credit loss on financing receivable from recovery.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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

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Amount of credit loss expense (reversal of expense) for financing receivable.

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