Borrowings (Federal Home Loan Bank Advances Maturity Schedule, Modification) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Federal Home Loan Bank, Advances, Fiscal Year Maturity [Abstract]
Federal Home Loan Bank advances	$ 406,297	$ 288,082
Federal Home Loan Bank of Boston [Member]
Federal Home Loan Bank, Advances, Fiscal Year Maturity [Abstract]
Scheduled Maturity, year two	63,130
Scheduled Maturity, year three	41,045
Scheduled Maturity, year four	64,803
Scheduled Maturity, year five	27,243
Federal Home Loan Bank advances	406,297	288,100
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate of Amounts Due [Abstract]
Weighted Average Rate, year two	2.31%
Weighted Average Rate, year three	3.16%
Weighted Average Rate, year four	3.85%
Weighted Average Rate, year five	4.31%
Weighted Average Rate, Total	1.89%
Federal Home Loan Bank of Boston [Member] \| Original Terms of FHLBB Advance Modification [Member]
Federal Home Loan Bank, Advances, Fiscal Year Maturity [Abstract]
Scheduled Maturity, year two	30,418
Scheduled Maturity, year three	10,000
Scheduled Maturity, year four	28,803
Scheduled Maturity, year five	0
Scheduled Maturity, year six	0
Schedule Maturity, year seven	0
Schedule Maturity, year eight	0
Federal Home Loan Bank advances	69,221
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate of Amounts Due [Abstract]
Weighted Average Rate, year two	3.44%
Weighted Average Rate, year three	3.87%
Weighted Average Rate, year four	4.79%
Weighted Average Rate, year five	0.00%
Weighted Average Rate, year six	0.00%
Weighted Average Rate, year seven	0.00%
Weighted Average Rate, year eight	0.00%
Weighted Average Rate, Total	4.06%
Federal Home Loan Bank of Boston [Member] \| Revised Terms of FHLBB Advance Modification [Member]
Federal Home Loan Bank, Advances, Fiscal Year Maturity [Abstract]
Scheduled Maturity, year two	0
Scheduled Maturity, year three	0
Scheduled Maturity, year four	5,000
Scheduled Maturity, year five	15,418
Scheduled Maturity, year six	10,000
Schedule Maturity, year seven	10,000
Schedule Maturity, year eight	28,803
Federal Home Loan Bank advances	$ 69,221
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate of Amounts Due [Abstract]
Weighted Average Rate, year two	0.00%
Weighted Average Rate, year three	0.00%
Weighted Average Rate, year four	2.43%
Weighted Average Rate, year five	2.87%
Weighted Average Rate, year six	3.13%
Weighted Average Rate, year seven	3.52%
Weighted Average Rate, year eight	4.14%
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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The weighted average interest rate applicable to the Federal Home Loan Bank advances which are due from four to five years of the Balance Sheet date.

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The weighted average interest rate applicable to the Federal Home Loan Bank advances which are due from one to two years of the Balance Sheet date.

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The weighted average interest rate applicable to the Federal Home Loan Bank advances which are due from three to four years of the Balance Sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.14)

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-Publisher SEC

-Name Industry Guide

-Number 3

-Section VII

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The weighted average interest rate applicable to the Federal Home Loan Bank advances which are due from two to three years of the Balance Sheet date.

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Amount of advances from Federal Home Loan Bank (FHLBank) maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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Amount of advances from Federal Home Loan Bank (FHLBank) maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of advances from Federal Home Loan Bank (FHLBank) maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of advances from Federal Home Loan Bank (FHLBank) maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Federal Home Loan Bank, Advances, Average Interest Rate, Due in Year Eight

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Federal Home Loan Bank, Advances, Average Interest Rate, Due in Year Seven

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

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Amount of advances from Federal Home Loan Bank (FHLBank) maturing in the eighth fiscal year following the latest fiscal year.

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Amount of advances from Federal Home Loan Bank (FHLBank) maturing in the seventh fiscal year following the latest fiscal year.

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Amount of advances from Federal Home Loan Bank (FHLBank) maturing in the sixth fiscal year following the latest fiscal year.

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Federal Hom Loan Bank, Advances, Average Interest Rate, Due in Year Six

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