Loan Portfolio and Credit Quality TDR Loans Restructured or Defaulted in Period (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) Loans		Mar. 31, 2015 USD ($) Loans	Dec. 31, 2015 USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 28,900			$ 30,600
Financing Receivable, Modifications, Number of Contracts | Loans	2		6
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 320		$ 382
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 145		$ 382
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Accruing Troubled Debt Restructured Loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 17,900			$ 18,600
Commercial and industrial [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans	1		0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 175		$ 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 and industrial [Member] | Extension of Term [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 and industrial [Member] | Temporary 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 and industrial [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 and industrial [Member] | Combination of Concessions [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans	1	[1]	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	[1]	$ 0
Commercial real estate [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 real estate [Member] | Extension of Term [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 [Member] | Temporary 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 [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 [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
Construction and land [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 and land [Member] | Extension of Term [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 and land [Member] | Temporary 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 and land [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 and land [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 [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans	1		6
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 145		$ 382
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 145		$ 382
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | Loans	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Residential [Member] | Extension of Term [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 [Member] | Temporary Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | Loans	1		6
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 145		$ 382
Residential [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
Residential [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 [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 [Member] | Extension of Term [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 [Member] | Temporary 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 [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 [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 and other [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 and other [Member] | Extension of Term [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 and other [Member] | Temporary 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 and other [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 and other [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.