Loans - Schedule of Loans Renegotiated in Troubled Debt Restructurings (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) note	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) note	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | note	3		5
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 3,900,000		$ 4,100,000
Loans renegotiated in troubled debt restructurings	30,300,000		30,300,000		$ 44,500,000
Loans renegotiated in troubled debt restructurings, non-accrual loans	24,400,000		24,400,000		31,900,000
Loans renegotiated in troubled debt restructurings, accrual loans	5,900,000		5,900,000		$ 12,600,000
Charge-offs directly related to modifying troubled debt restructurings	0	$ 0	0	$ 0
Balance of defaulted loans under trouble debt restructurings			0
Commitments to lend additional funds	$ 0		$ 0
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | note	3		5
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 3,900,000		$ 4,100,000
Interest Only Period Concession [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	3,400,000		3,600,000
Interest Only Period Concession [Member] | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	3,400,000		3,600,000
Extended Maturity [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	0		0
Extended Maturity [Member] | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	0		0
Contractual Interest Rate Reduction [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	0		0
Contractual Interest Rate Reduction [Member] | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	0		0
Other Concession [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	500,000		500,000
Other Concession [Member] | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 500,000		$ 500,000