Loans and Credit Quality - Troubled Debt Restructured Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Modifications [Line Items]
New troubled debt restructurings	$ 4,368
Existing troubled debt restructurings	11,851
Total modifications	16,219	$ 13,740
Commercial | Asset Quality Rating - Substandard
Financing Receivable, Modifications [Line Items]
New troubled debt restructurings	4,368
Accrual Status
Financing Receivable, Modifications [Line Items]
New troubled debt restructurings	4,234
Existing troubled debt restructurings	1,897
Total modifications	6,131
Accrual Status | Commercial | Asset Quality Rating - Substandard
Financing Receivable, Modifications [Line Items]
New troubled debt restructurings	4,234
Nonaccrual Status
Financing Receivable, Modifications [Line Items]
New troubled debt restructurings	134
Existing troubled debt restructurings	9,954
Total modifications	10,088
Nonaccrual Status | Commercial | Asset Quality Rating - Substandard
Financing Receivable, Modifications [Line Items]
New troubled debt restructurings	$ 134