Loans (Details 4) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013 item	Mar. 31, 2012	Dec. 31, 2012 item
Loans categorized as a troubled debt restructurings
Number of loans classified as troubled debt restructuring	26		25
Loans classified as troubled debt restructuring	$ 14,900,000		$ 15,900,000
Percentage of total gross loans representing troubled debt restructurings	1.60%		1.80%
Additional loans modified and designated as troubled debt restructurings	0
Charge-off		750,000
Loans modified within the last twelve months that defaulted	0
Pre-Modification Investment	20,103,000		21,080,000
Post-Modification Investment	14,936,000		15,861,000
Performing
Loans categorized as a troubled debt restructurings
Pre-Modification Investment	9,794,000		10,771,000
Post-Modification Investment	8,798,000		9,402,000
Nonaccrual
Loans categorized as a troubled debt restructurings
Pre-Modification Investment	10,309,000		10,309,000
Post-Modification Investment	6,138,000		6,459,000
Commercial
Loans categorized as a troubled debt restructurings
Number of loans classified as troubled debt restructuring	2		2
Pre-Modification Investment	2,598,000		2,598,000
Post-Modification Investment	450,000		676,000
Commercial | Nonaccrual
Loans categorized as a troubled debt restructurings
Pre-Modification Investment	2,598,000		2,598,000
Post-Modification Investment	450,000		676,000
Real estate other
Loans categorized as a troubled debt restructurings
Number of loans classified as troubled debt restructuring	21		23
Commitments to lend additional funds	111,000		111,000
Pre-Modification Investment	17,025,000		18,002,000
Post-Modification Investment	13,990,000		14,685,000
Real estate other | Performing
Loans categorized as a troubled debt restructurings
Pre-Modification Investment	9,314,000		10,291,000
Post-Modification Investment	8,302,000		8,902,000
Real estate other | Nonaccrual
Loans categorized as a troubled debt restructurings
Pre-Modification Investment	7,711,000		7,711,000
Post-Modification Investment	5,688,000		5,783,000
SBA
Loans categorized as a troubled debt restructurings
Number of loans classified as troubled debt restructuring	3		3
Loans classified as troubled debt restructuring		38,000
Pre-Modification Investment	480,000		480,000
Post-Modification Investment	496,000		500,000
SBA | Performing
Loans categorized as a troubled debt restructurings
Pre-Modification Investment	480,000		480,000
Post-Modification Investment	496,000		500,000
Factoring and asset based
Loans categorized as a troubled debt restructurings
Loans classified as troubled debt restructuring		$ 2,300,000