Mortgage Banking (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Dec. 31, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Mortgage servicing rights [Abstract]
Balance at beginning of period				$ 51,151,000	$ 50,513,000
Origination of servicing assets				9,581,000	12,752,000
Disposals of mortgage loans sold serviced released				0	(1,681,000)
Due to market changes				(12,288,000)	(14,813,000)
Due to runoff				(4,785,000)	(4,799,000)
Balance at end of period	51,151,000	43,659,000	41,972,000	43,659,000	41,972,000
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net		2,800,000	2,900,000	4,800,000	7,600,000
Proceeds from sale of loans serviced for others					920,900,000
Reduction in Fair Value of MSR's due to sale of assets serviced					8,500,000
Payments to acquire loans receivable	53,900,000
Mortgage loan servicing representation and warranty expenses incurred				2,500,000	1,100,000
Accrual for mortgage loan servicing representation and warranty expenses	$ 900,000	$ 2,000,000		$ 2,000,000