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Loans and Allowance for Loan Losses - CARES Act Narrative (Details) $ in Thousands	1 Months Ended	7 Months Ended
	Oct. 31, 2020	Sep. 30, 2020 USD ($) loan	Oct. 19, 2020 USD ($) loan	Jun. 30, 2020 loan	Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payroll Protection Program loans, balance		$ 2,107,991			$ 1,843,286
Number of loan modifications under CARES Act | loan		264
Payment deferral period, loans modified under CARES Act		120 days
Total loan balance modified under CARES Act		$ 388,500
SBA PPP
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans (over) | loan				1,800
Commercial loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payroll Protection Program loans, balance		512,973			$ 246,687
Commercial loans | Commercial and industrial | SBA PPP
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payroll Protection Program loans, balance		$ 301,700
Subsequent event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan modifications under CARES Act, additional relief | loan			20
Loans and leases receivable, net of deferred income, modified under CARES Act, additional relief			$ 47,200
Subsequent event | SBA PPP
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment deferral period, before extension due to PPP forgiveness process delay	6 months
Payment deferral period, before extension due to PPP forgiveness process delay	16 months

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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