Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Fair Value of Financial Instruments
Cost to assume off-balance sheet commitments and standby letters of credit as a percentage of notional amount	10.00%
Assets:
Federal Reserve Bank and FHLB stock, at cost	$ 12,191	$ 12,982	$ 12,475
Accrued interest receivable	3,933	3,732	3,885
Off-balance sheet commitments and standby letters of credit
Notional Amount	152,057	61,986	73,053
Cost to Cede or Assume	15,206	6,199	7,305
Carrying Amount
Assets:
Cash and cash equivalents	58,243	37,808	60,235
Securities available for sale	114,250	107,761	115,645
Federal Reserve Bank and FHLB stock, at cost	12,191	12,982	12,475
Loans held for sale, net	4,728
Loans held for investment, net	851,715	725,952	730,067
Accrued interest receivable	3,933	3,732	3,885
Liabilities:
Deposit accounts	895,870	797,378	828,877
FHLB advances	47,000
Other borrowings	28,500	28,500	28,500
Subordinated debentures	10,310	10,310	10,310
Accrued interest payable	213	153	147
Estimated Fair Value
Assets:
Cash and cash equivalents	58,243	37,808	60,235
Securities available for sale	114,250	107,761	115,645
Federal Reserve Bank and FHLB stock, at cost	12,191	12,982	12,475
Loans held for sale, net	4,728
Loans held for investment, net	931,640	795,427	794,906
Accrued interest receivable	3,933	3,732	3,885
Liabilities:
Deposit accounts	898,888	802,202	833,241
FHLB advances	47,000
Other borrowings	32,360	31,603	31,361
Subordinated debentures	8,222	7,500	5,405
Accrued interest payable	$ 213	$ 153	$ 147