Loans and Leases and Allowance for Credit Losses - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Pledged as collateral to secure contingent funding sources	$ 4,150,000,000		$ 4,060,000,000.00
Net investment in leases	37,560,000		37,378,000
Carrying value of purchased credit impaired loans			58,646,000
Gross additional interest revenue that would have been earned if the nonaccrual loans had performed as per original terms	468,000	$ 378,000
TDRs	53,700,000		54,200,000
Allocated allowance for TDRs	1,510,000		2,510,000
Commitments to lend additional amounts to customers with outstanding loans classified as TDRs	0		0
Amount of loans	8,853,519,000		8,750,464,000
SBA/USDA guaranteed loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans sold	4,030,000.00	$ 17,100,000
Equipment financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans sold	22,200,000
Loans receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of purchased credit impaired loans			58,646,000
Unpaid principal balance of purchased credit impaired (PCI) loans			$ 83,100,000
Performing | Short-term deferrals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount of loans	$ 164,000,000