Loans and Credit Quality - Newly Restructured Loans by Concession (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($) contract	Sep. 30, 2017 USD ($) contract
Financing Receivable, Modifications [Line Items]
Pre-modification, number of contracts | contract	6	3
Pre-modification, total modification	$ 4,398	$ 12,953
Post-modification, number of contracts | contract	6	3
Post-modification, total modification	$ 3,432	$ 11,382
Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, number of contracts | contract	4	2
Pre-modification, total modification	$ 2,704	$ 10,875
Post-modification, number of contracts | contract	4	2
Post-modification, total modification	$ 1,738	$ 9,304
Commercial | 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
Real estate term owner occupied | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, number of contracts | contract	2
Pre-modification, total modification	$ 1,694
Post-modification, number of contracts | contract	2
Post-modification, total modification	$ 1,694
Rate Modification
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0	0
Post-modification, total modification	0	0
Rate Modification | Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0	0
Post-modification, total modification	0	0
Rate Modification | Commercial | AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification		0
Post-modification, total modification		0
Rate Modification | Real estate term owner occupied | 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	0	12,743
Post-modification, total modification	0	11,177
Term Modification | Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0	10,665
Post-modification, total modification	0	9,099
Term Modification | Commercial | AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification		2,078
Post-modification, total modification		2,078
Term Modification | Real estate term owner occupied | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	0
Payment Modification
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	4,398	210
Post-modification, total modification	3,432	205
Payment Modification | Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	2,704	210
Post-modification, total modification	1,738	205
Payment Modification | Commercial | AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification		0
Post-modification, total modification		0
Payment Modification | Real estate term owner occupied | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	1,694
Post-modification, total modification	1,694
Combination Modification
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0	0
Post-modification, total modification	0	0
Combination Modification | Commercial | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0	0
Post-modification, total modification	0	0
Combination Modification | Commercial | AQR Special Mention
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification		0
Post-modification, total modification		$ 0
Combination Modification | Real estate term owner occupied | AQR Substandard
Financing Receivable, Modifications [Line Items]
Pre-modification, total modification	0
Post-modification, total modification	$ 0