Loans and Credit Quality - Newly Restructured Loans by Concession (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) contract
Financing Receivable, Modifications [Line Items]
Pre-modification, number of contracts | contract	3
Pre-modification, total modification	$ 12,953
Post-modification, number of contracts | contract	3
Post-modification, total modification	$ 11,382
AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, number of contracts | contract	1
Pre-modification, total modification	$ 2,078
Post-modification, number of contracts | contract	1
Post-modification, total modification	$ 2,078
Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, number of contracts | contract	2
Pre-modification, total modification	$ 10,875
Post-modification, number of contracts | contract	2
Post-modification, total modification	$ 9,304
Rate Modification
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	0
Rate Modification | AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	0
Rate Modification | Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	0
Term Modification
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	12,743
Post-modification, total modification	11,177
Term Modification | AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	2,078
Post-modification, total modification	2,078
Term Modification | Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	10,665
Post-modification, total modification	9,099
Payment Modification
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	210
Post-modification, total modification	205
Payment Modification | AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	0
Payment Modification | Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	210
Post-modification, total modification	205
Combination Modification
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	0
Combination Modification | AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	0
Combination Modification | Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	$ 0