Loans and Leases and Allowance for Credit Losses - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Pledged as collateral to secure contingent funding sources	$ 4,050,000,000.00		$ 4,050,000,000.00		$ 4,060,000,000.00
Carrying value of PCI loans					58,646,000
Net investment in leases	36,644,000		36,644,000		37,378,000
Gross additional interest revenue that would have been earned if the nonaccrual loans had performed as per original terms	570,000	$ 338,000	1,700,000	$ 965,000
TDRs	54,500,000		54,500,000		54,200,000
Allocated allowance for TDRs	927,000		927,000		2,510,000
Commitments to lend additional amounts to customers with outstanding loans classified as TDRs	14,000		14,000		0
SBA/USDA guaranteed loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans sold	13,500,000	$ 21,000,000.0	31,500,000	$ 55,200,000
Equipment financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans sold	950,000		24,900,000
Loans receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of PCI loans					58,646,000
Outstanding balance of PCI loans					$ 83,100,000
Short-term deferrals related to COVID-19 crisis	$ 365,000,000		$ 365,000,000