Borrowings (Narrative - Federal Home Loan Bank Advances) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank advances	$ 406,297,000	$ 288,082,000
Federal Home Loan Bank of Boston [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank advances	406,297,000	288,100,000
Unused line of credit with Federal Home Loan Bank	40,000,000	8,000,000
Line of Credit Facility, Remaining Borrowing Capacity	569,400,000	564,100,000
Weighted Average Rate, Total	1.89%
Original Terms of FHLBB Advance Modification [Member] \| Federal Home Loan Bank of Boston [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank advances	69,221,000
Weighted Average Rate, Total	4.06%
Revised Terms of FHLBB Advance Modification [Member] \| Federal Home Loan Bank of Boston [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank advances	$ 69,221,000
Weighted Average Rate, Total	3.50%

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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- Definition

Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 45

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-Number 210

-Section 02

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

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Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, Total

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