Loans and Loans Held for Sale - Summary of Restructured Loans (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Restructured loans	[1]	$ 1,471	$ 5,005	$ 4,522	$ 15,775
Performing TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans				15,605		$ 13,423
Performing TDRs | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Restructured loans				2,618		2,994
Performing TDRs | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Restructured loans				4,063		1,387
Performing TDRs | Commercial Construction
Financing Receivable, Modifications [Line Items]
Restructured loans				2,914		2,966
Performing TDRs | Residential Mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans				2,096		2,375
Performing TDRs | Home Equity
Financing Receivable, Modifications [Line Items]
Restructured loans				3,871		3,683
Performing TDRs | Installment and Other Consumer
Financing Receivable, Modifications [Line Items]
Restructured loans				43		18
Nonperforming TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans				10,203		11,598
Nonperforming TDRs | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Restructured loans				1,083		646
Nonperforming TDRs | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Restructured loans				3,580		4,493
Nonperforming TDRs | Commercial Construction
Financing Receivable, Modifications [Line Items]
Restructured loans				421		430
Nonperforming TDRs | Residential Mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans				4,095		5,068
Nonperforming TDRs | Home Equity
Financing Receivable, Modifications [Line Items]
Restructured loans				1,013		954
Nonperforming TDRs | Installment and Other Consumer
Financing Receivable, Modifications [Line Items]
Restructured loans				11		7
Total TDRs
Financing Receivable, Modifications [Line Items]
Restructured loans				25,808		25,021
Total TDRs | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Restructured loans				3,701		3,640
Total TDRs | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Restructured loans				7,643		5,880
Total TDRs | Commercial Construction
Financing Receivable, Modifications [Line Items]
Restructured loans				3,335		3,396
Total TDRs | Residential Mortgage
Financing Receivable, Modifications [Line Items]
Restructured loans				6,191		7,443
Total TDRs | Home Equity
Financing Receivable, Modifications [Line Items]
Restructured loans				4,884		4,637
Total TDRs | Installment and Other Consumer
Financing Receivable, Modifications [Line Items]
Restructured loans				$ 54		$ 25

[1] Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.