Deferred Tax Assets and Income Taxes (Details) (USD $)	3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2011	Jun. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2009
Deferred tax assets
Provision for loan losses	$ 8,669,000				$ 8,669,000		$ 14,348,000
Forgone interest on non-accrual loans	855,000				855,000		884,000
Fixed assets	459,000				459,000		405,000
Accruals	929,000				929,000		792,000
Alternative minimum tax credit	2,855,000				2,855,000		2,153,000
Deferred income	2,129,000				2,129,000		1,838,000
Deferred compensation	1,602,000				1,602,000		1,477,000
Net operating loss carryforward	6,000				6,000		907,000
Investment securities valuation	2,037,000				2,037,000
Other than temporary impairment							45,000
Realized built-in loss subject to 382	2,433,000				2,433,000		3,234,000
Charitable contribution							61,000
State deferred tax	781,000				781,000		59,000
Total deferred tax assets	22,755,000				22,755,000		26,203,000
Deferred tax liabilities
Fair value adjustment for purchased assets	362,000				362,000		455,000
Investment securities valuation							2,745,000
Deferred costs, prepaids and FHLB advances	1,032,000				1,032,000		1,070,000
Total deferred tax liabilities	1,394,000				1,394,000		4,270,000
Net deferred tax assets	21,361,000				21,361,000		21,933,000
Cumulative loss position period								3 years	3 years
Change in deferred tax asset valuation allowance		(4,100,000)	(1,500,000)	(1,500,000)			(5,600,000)	7,100,000
Determination of the valuation allowance, cumulative pre-tax losses period								3 years
Determination of the valuation allowance, expected deferred tax assets realization period								5 years
Current:
Federal	495,000	936,000			306,000	2,489,000
State	(249,000)	485,000			29,000	957,000
Total current (benefit) / expense	246,000	1,421,000			335,000	3,446,000
Deferred:
Federal	630,000	(141,000)			3,777,000	(1,061,000)
State	717,000	(115,000)			1,577,000	(288,000)
Total deferred expense / (benefit)	1,347,000	(256,000)			5,354,000	(1,349,000)
Deferred Tax Valuation Allowance:
Federal		(2,552,000)				(3,662,000)
State		(1,553,000)				(1,943,000)
Total deferred tax valuation allowance change		(4,105,000)				(5,605,000)
Total income tax expense / (benefit)	1,593,000	(2,940,000)			5,689,000	(3,508,000)
Reconciliation of the statutory federal income tax expense / (benefit) to the Company's effective income tax expense / (benefit)
Tax expense at federal statutory tax rate	1,525,000	1,221,000			5,214,000	2,241,000
State income taxes, net of federal income tax benefit	304,000	241,000			1,044,000	435,000
Change in deferred tax asset valuation allowance		(4,105,000)				(5,605,000)
Bank owned life insurance	(38,000)	(56,000)			(115,000)	(109,000)
Tax exempt income, net of interest expense	(176,000)	(217,000)			(402,000)	(415,000)
Other, net	(22,000)	(24,000)			(52,000)	(55,000)
Total income tax expense / (benefit)	$ 1,593,000	$ (2,940,000)			$ 5,689,000	$ (3,508,000)
Reconciliation of the statutory federal income tax expense / (benefit) rate to the Company's effective income tax expense / (benefit) rate
Tax expense at federal statutory tax rate (as a percent)	35.00%	35.00%			35.00%	35.00%
State income taxes, net of federal income tax benefit (as a percent)	7.00%	6.90%			7.00%	6.80%
Change in deferred tax asset valuation allowance (as a percent)	0.00%	(117.70%)			0.00%	(87.60%)
Bank owned life insurance (as a percent)	(0.90%)	(1.60%)			(0.80%)	(1.70%)
Tax exempt income, net of interest expense (as a percent)	(4.00%)	(6.20%)			(2.70%)	(6.50%)
Other, net (as a percent)	(0.50%)	(0.70%)			(0.30%)	(0.80%)
Total income tax expense / (benefit) (as a percent)	36.60%	(84.30%)			38.20%	(54.80%)