Loans Receivable and Credit Quality Troubled Debt Restructured Loans (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2016 USD ($) Loans	Dec. 31, 2015 USD ($) Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		9	11
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 10,369	$ 6,661
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 10,206	$ 6,658
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		1	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 1,276	$ 3,701
Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		3	1
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 7,384	$ 1,298
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 7,209	$ 1,304
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0
Commercial Loan [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		2	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 7,209	$ 0
Commercial Loan [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Commercial Loan [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Commercial Loan [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans	[1]	1	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	[1]	$ 0	$ 1,304
Commercial Tax Exempt [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0
Commercial Tax Exempt [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Commercial Tax Exempt [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Commercial Tax Exempt [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Commercial Tax Exempt [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		1	2
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 1,276	$ 4,850
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 1,276	$ 4,838
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		1	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 1,276	$ 3,701
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 4,118
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Commercial Real Estate Portfolio Segment [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans	[1]	1	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	[1]	$ 1,276	$ 720
Construction Loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0
Construction Loans [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Construction Loans [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Construction Loans [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Construction Loans [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		5	8
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 1,709	$ 513
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 1,721	$ 516
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		4	7
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 519	$ 491
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		1	1
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 1,202	$ 25
Residential Portfolio Segment [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0
Home Equity Line of Credit [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Home Equity Line of Credit [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Home Equity Line of Credit [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Home Equity Line of Credit [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0
Consumer Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Consumer Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Consumer Portfolio Segment [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0
Consumer Portfolio Segment [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0

[1] Combination of concessions includes loans that have had more than one modification, including extension of term, temporary reduction of interest rate, and/or payment deferral.