Loan Portfolio and Credit Quality TDR Loans Restructured or Defaulted in Period (Details) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016 USD ($) Loans	Sep. 30, 2015 USD ($) Loans	Sep. 30, 2016 USD ($) Loans		Sep. 30, 2015 USD ($) Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	1	6		11
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 732	$ 8,920		$ 6,661
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 720	$ 8,746		$ 6,658
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		1	0	1		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 1,276	$ 0	$ 1,276		$ 0
Commercial and industrial [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0	3		1
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0	$ 7,384		$ 1,298
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0	$ 7,209		$ 1,304
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0	$ 0		$ 0
Commercial and industrial [Member] | Extension of Term [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	2		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 7,209		$ 0
Commercial and industrial [Member] | Temporary Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Commercial and industrial [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Commercial and industrial [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	1	[1]	1	[1]
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0	[1]	$ 1,304	[1]
Commercial real estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	1	1		2
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 732	$ 1,276		$ 4,850
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 720	$ 1,276		$ 4,838
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		1	0	1		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 1,276	$ 0	$ 1,276		$ 0
Commercial real estate [Member] | Extension of Term [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		1
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 4,118
Commercial real estate [Member] | Temporary Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Commercial real estate [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Commercial real estate [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans	[1]		1	1		1
Financing Receivable, Modifications, Post-Modification Recorded Investment	[1]		$ 720	$ 1,276		$ 720
Construction and land [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0	0		0
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0	$ 0		$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0	$ 0		$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0	$ 0		$ 0
Construction and land [Member] | Extension of Term [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Construction and land [Member] | Temporary Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Construction and land [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Construction and land [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Residential [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0	2		8
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0	$ 260		$ 513
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0	$ 261		$ 516
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0	$ 0		$ 0
Residential [Member] | Extension of Term [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Residential [Member] | Temporary Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	2		7
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 261		$ 491
Residential [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		1
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 25
Residential [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Home equity [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0	0		0
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0	$ 0		$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0	$ 0		$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0	$ 0		$ 0
Home equity [Member] | Extension of Term [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Home equity [Member] | Temporary Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Home equity [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Home equity [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Consumer and other [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans		0	0	0		0
Financing Receivable, Modifications, Pre-Modification Recorded Investment		$ 0	$ 0	$ 0		$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment		$ 0	$ 0	$ 0		$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans		0	0	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment		$ 0	$ 0	$ 0		$ 0
Consumer and other [Member] | Extension of Term [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Consumer and other [Member] | Temporary Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Consumer and other [Member] | Payment Deferral [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 0		$ 0
Consumer and other [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans			0	0		0
Financing Receivable, Modifications, Post-Modification Recorded Investment			$ 0	$ 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.