Borrowings (Federal Home Loan Bank Advances Maturity Schedule) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Federal Home Loan Bank, Advances, Fiscal Year Maturity [Abstract]
Scheduled Maturity, Total	$ 361,172		$ 540,450
Federal Home Loan Bank of Boston [Member]
Federal Home Loan Bank, Advances, Fiscal Year Maturity [Abstract]
Scheduled Maturity, next 12 months	48,630		138,965
Scheduled Maturity, year two	2,519		44,757
Scheduled Maturity, year three	79,069		88,109
Scheduled Maturity, year four	85,066		132,682
Scheduled Maturity, year five	80,335		92,124
Scheduled Maturity, year six			5,849
Scheduled Maturity, after year five	65,553
Scheduled Maturities, after year six			37,964
Scheduled Maturity, Total	361,172		540,450
Federal Home Loan Bank, Advances, Maturities Summary, Redeemed Call Date of Amounts Due [Abstract] [Abstract]
Redeemed at Call Date, next 12 months	48,630	[1]	143,965	[1]
Redeemed at Call Date, year two	2,519	[1]	39,757	[1]
Redeemed at Call Date, year three	79,069	[1]	88,109	[1]
Redeemed at Call Date, year four	85,066	[1]	132,682	[1]
Redeemed at Call Date, year five	80,335	[1]	92,124	[1]
Redeemed at Call Date, year six			5,849	[1]
Redeemed at Call Date, after year five	65,553	[1]
Redeemed at Call Date, after year six			37,964	[1]
Redeemed at Call Date, Total	$ 361,172	[1]	$ 540,450	[1]
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate of Amounts Due [Abstract]
Weighted Average Rate, next 12 months	0.81%	[2]	1.07%	[2]
Weighted Average Rate, year two	3.54%	[2]	3.36%	[2]
Weighted Average Rate, year three	3.63%	[2]	3.54%	[2]
Weighted Average Rate, year four	3.05%	[2]	3.54%	[2]
Weighted Average Rate, year five	2.94%	[2]	3.66%	[2]
Weighted Average Rate, year six			5.57%	[2]
Weighted Average Rate, after year five	4.58%	[2]
Weighted Average Rate, after year six			4.86%	[2]
Weighted Average Rate, Total	3.13%		3.03%

[1] Callable FHLBB advances are shown in the respective periods assuming that the callable debt is redeemed at the call date while all other advances are shown in the periods corresponding to their scheduled maturity date.

[2] Weighted average rate based on scheduled maturity dates.