Investment Securities (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales of available for sale debt securities	$ 27,030,000	$ 54,540,000	$ 41,660,000	$ 77,030,000
Available-for-sale securities, gross realized gains	372,000	204,000	494,000	218,000
Available-for-sale securities, gross realized losses	0	67,000	46,000	91,000
Investment in FHLBB stock					8,630,000
Investment in FHLBB stock, period decrease			485,000	0
Dividend income on investment in federal home loan bank stock	8,000	6,000	25,000	13,000
Non-Agency CMO Portfolio [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost basis	4,900,000		4,900,000
Non-Agency CMO Portfolio [Member] | Bond 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost basis	3,270,000		3,270,000
Bond, fair value	3,170,000		3,170,000
Non-Agency CMO Portfolio [Member] | Bond 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost basis	1,630,000		1,630,000
Bond, fair value	$ 1,560,000		$ 1,560,000