Investment Securities - Amortized cost and approximate fair values of securities (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 128,428,000	$ 110,822,000
Gross Unrealized Gains	1,628,000	3,535,000
Gross Unrealized Losses	(3,748,000)	(587,000)
Fair Value	126,308,000	113,770,000
Federal agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	45,536,000	42,581,000
Gross Unrealized Gains	392,000	849,000
Gross Unrealized Losses	(988,000)	(21,000)
Fair Value	44,940,000	43,409,000
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	34,920,000	29,331,000
Gross Unrealized Gains	829,000	1,865,000
Gross Unrealized Losses	(1,363,000)	(34,000)
Fair Value	34,386,000	31,162,000
Government-sponsored enterprise (GSE) residential mortgage-backed and other asset-backed agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	44,809,000	35,258,000
Gross Unrealized Gains	405,000	774,000
Gross Unrealized Losses	(950,000)	(10,000)
Fair Value	44,264,000	36,022,000
Corporate
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,163,000	3,652,000
Gross Unrealized Gains	2,000	47,000
Gross Unrealized Losses	(447,000)	(522,000)
Fair Value	$ 2,718,000	$ 3,177,000