Investment Securities (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 item	Dec. 31, 2012	Mar. 31, 2012
Investment securities available for sale:
Amortized Cost	$ 298,499,000	$ 82,189,000	$ 150,062,000
Unrealized Gain	3,615,000	2,360,000	1,757,000
Unrealized Loss	(954,000)	(483,000)	(1,080,000)
Estimated Fair Value	301,160,000	84,066,000	150,739,000
Stock, Amortized Cost
FHLB stock	8,955,000	9,228,000	9,956,000
Federal Reserve Bank stock	2,019,000	2,019,000	2,019,000
Total stock	10,974,000	11,247,000	11,975,000
Stock, Estimated Fair Value
FHLB stock	8,955,000	9,228,000	9,956,000
Federal Reserve Bank stock	2,019,000	2,019,000	2,019,000
Total stock	10,974,000	11,247,000	11,975,000
Total securities
Amortized Cost	309,473,000	93,436,000	162,037,000
Estimated Fair Value	312,134,000	95,313,000	162,714,000
Additional disclosures
Excess FHLB stock with the entity repurchased by FHLB through their stock repurchase program	273,000
Number of inverse putable reverse repurchases of the Bank's secured by collateral	3
Value of inverse putable reverse repurchases secured by collateral	28,500,000
U.S. Treasury
Investment securities available for sale:
Amortized Cost	74,000	147,000	147,000
Unrealized Gain	11,000	12,000	13,000
Estimated Fair Value	85,000	159,000	160,000
Corporate
Investment securities available for sale:
Amortized Cost			5,000,000
Unrealized Loss			(183,000)
Estimated Fair Value			4,817,000
Municipal bonds
Investment securities available for sale:
Amortized Cost	154,543,000	25,401,000	26,940,000
Unrealized Gain	1,783,000	1,186,000	851,000
Unrealized Loss	(387,000)	(1,000)	(96,000)
Estimated Fair Value	155,939,000	26,586,000	27,695,000
Mortgage-backed securities
Investment securities available for sale:
Amortized Cost	143,882,000	56,641,000	117,975,000
Unrealized Gain	1,821,000	1,162,000	893,000
Unrealized Loss	(567,000)	(482,000)	(801,000)
Estimated Fair Value	145,136,000	57,321,000	118,067,000
Additional disclosures
Estimated par value of securities pledged as collateral for the Bank's inverse putable reverse repurchases	41,100,000
Fair value of securities pledged as collateral for the Bank's inverse putable reverse repurchases	$ 42,500,000