Bank subsidiary (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2009	Dec. 31, 2010
Amortized Cost
Due after one year through five years	$ 208,342,000
Due after five years through ten years	58,113,000
Due after ten years	7,280,000
Total amortized cost	273,735,000
Mortgage-related securities-FNMA, FHLMC and GNMA - amortized cost	334,183,000
Total available-for-sale securities, amortized cost	607,918,000		672,288,000
Fair value
Due after one year through five years	210,106,000
Due after five years through ten years	61,585,000
Due after ten years	7,775,000
Total fair value	279,466,000
Mortgage-related securities-FNMA, FHLMC and GNMA - fair value	344,865,000
Total available for sale securities	624,331,000		678,152,000
Available-for-sale Securities, Continuous Unrealized Loss Position
Gross unrealized losses, less than 12 months	(25,000)		(3,884,000)
Fair value, less than 12 months	31,986,000		277,781,000
Proceeds from sales of available-for-sale	32,799,000	185,134,000
Available-for-sale securities pledged at carrying value	91,900,000		60,800,000
Available-for-sale securities, pledged at carrying value as collateral for securities sold under agreements to repurchase	219,700,000		204,800,000
Federal agency obligations
Amortized Cost
Total available-for-sale securities, amortized cost	218,342,000		317,945,000
Fair value
Total available for sale securities	220,727,000		315,896,000
Available-for-sale Securities, Continuous Unrealized Loss Position
Gross unrealized losses, less than 12 months	(8,000)		(2,220,000)
Fair value, less than 12 months	19,992,000		205,316,000
Mortgage-related securities - FNMA, FHLMC and GNMA
Amortized Cost
Total available-for-sale securities, amortized cost	334,183,000		310,711,000
Fair value
Total available for sale securities	344,865,000		319,970,000
Available-for-sale Securities, Continuous Unrealized Loss Position
Gross unrealized losses, less than 12 months	(17,000)		(311,000)
Fair value, less than 12 months	11,994,000		30,986,000
Proceeds from sales of available-for-sale	30,700,000	185,100,000
Gross realized gains	400,000	800,000
Gross realized losses		32,900,000
Municipal bonds
Amortized Cost
Total available-for-sale securities, amortized cost	55,393,000		43,632,000
Fair value
Total available for sale securities	58,739,000		42,286,000
Available-for-sale Securities, Continuous Unrealized Loss Position
Gross unrealized losses, less than 12 months			(1,353,000)
Fair value, less than 12 months			41,479,000
Proceeds from sales of available-for-sale	2,100,000
Gross realized gains	$ 5,000