Loans (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Recorded investment
Loans with no related allowance recorded	$ 14,087,000	$ 9,557,000	$ 9,935,000
Loans with an allowance recorded	15,242,000	12,582,000	7,335,000
Total	29,329,000	22,139,000	17,270,000
Unpaid principal balance
Loans with no related allowance recorded	17,555,000	9,783,000	12,277,000
Loans with an allowance recorded	19,186,000	18,477,000	7,527,000
Total	36,741,000	28,260,000	19,804,000
Related allowance	3,617,000	2,561,000	1,814,000
Average recorded investment
Loans with no related allowance recorded	13,741,000	9,366,000	6,229,000
Loans with an allowance recorded	15,368,000	9,726,000	8,011,000
Total	29,109,000	19,092,000	14,240,000
Additional disclosure
Interest income on impaired or non-accrual loans (cash basis)	157,000	391,000	250,000
Interest income that would have been recorded if non-accrual loans were on a current basis	1,167,000	1,104,000	1,192,000
Loans past due more than 90 days or more and still accruing interest	719,000	1,160,000
Recorded investment in non-accrual loans	18,360,000	18,737,000
Commercial and industrial
Recorded investment
Loans with no related allowance recorded	6,735,000	694,000	420,000
Loans with an allowance recorded	1,932,000	4,765,000	100,000
Total	8,667,000	5,459,000	520,000
Unpaid principal balance
Loans with no related allowance recorded	7,591,000	920,000	1,982,000
Loans with an allowance recorded	5,103,000	6,415,000	292,000
Total	12,694,000	7,335,000	2,274,000
Related allowance	156,000	954,000	90,000
Average recorded investment
Loans with no related allowance recorded	6,226,000	951,000	250,000
Loans with an allowance recorded	3,294,000	2,447,000	373,000
Total	9,520,000	3,398,000	623,000
Additional disclosure
Recorded investment in non-accrual loans	1,554,000	2,665,000
Construction and development
Recorded investment
Loans with no related allowance recorded	352,000	2,316,000	700,000
Loans with an allowance recorded	10,511,000	100,000
Total	10,863,000	2,416,000	700,000
Unpaid principal balance
Loans with no related allowance recorded	2,187,000	2,316,000	700,000
Loans with an allowance recorded	11,135,000	100,000
Total	13,322,000	2,416,000	700,000
Related allowance	2,898,000	10,000
Average recorded investment
Loans with no related allowance recorded	2,097,000	1,979,000	350,000
Loans with an allowance recorded	5,929,000	20,000	2,123,000
Total	8,026,000	1,999,000	2,473,000
Additional disclosure
Recorded investment in non-accrual loans	10,863,000	2,416,000
Real estate mortgage
Recorded investment
Loans with no related allowance recorded	6,996,000	6,453,000	8,720,000
Loans with an allowance recorded	2,799,000	7,717,000	7,235,000
Total	9,795,000	14,170,000	15,955,000
Unpaid principal balance
Loans with no related allowance recorded	7,752,000	6,453,000	9,455,000
Loans with an allowance recorded	2,948,000	11,962,000	7,235,000
Total	10,700,000	18,415,000	16,690,000
Related allowance	563,000	1,597,000	1,724,000
Average recorded investment
Loans with no related allowance recorded	5,397,000	6,353,000	5,565,000
Loans with an allowance recorded	6,145,000	7,249,000	5,515,000
Total	11,542,000	13,602,000	11,080,000
Additional disclosure
Loans past due more than 90 days or more and still accruing interest	485,000	1,160,000
Recorded investment in non-accrual loans	5,939,000	13,562,000
Consumer
Recorded investment
Loans with no related allowance recorded	4,000	94,000	95,000
Total	4,000	94,000	95,000
Unpaid principal balance
Loans with no related allowance recorded	25,000	94,000	140,000
Total	25,000	94,000	140,000
Average recorded investment
Loans with no related allowance recorded	21,000	83,000	64,000
Loans with an allowance recorded		10,000
Total	21,000	93,000	64,000
Additional disclosure
Loans past due more than 90 days or more and still accruing interest	234,000
Recorded investment in non-accrual loans	$ 4,000	$ 94,000