Mortgage Banking Activities, Loans Sold With Recourse (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Mar. 31, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Activity in the allowance for losses on loans sold with recourse [Roll forward]
Beginning balance	$ 16,487,000	$ 13,781,000	$ 13,781,000	$ 16,667,000	$ 13,781,000
Provision for recourse losses	2,532,000	1,568,000		3,326,000	2,867,000
Loans charged off, net	(1,479,000)	(1,568,000)		(2,453,000)	(2,867,000)
Ending balance	17,540,000	13,781,000	13,781,000	17,540,000	13,781,000
Number of residential mortgage loans purchased for servicing			34,000
Principal balance of residential mortgage loans purchased for servicing			4,200,000,000
Payments to acquire mortgage servicing rights (MSR)			32,000,000
Servicing asset at fair value, additions			43,700,000
Servicing asset acquired variance between fair value and acquisition price			11,800,000
Economic hedge threshold for interest rate sensitivity for mortgage servicing rights and securities held (in basis points)	50 BPS			50 BPS
Dollar increase in fair value, net of economic hedge, of mortgage servicing rights due to 50 basis point increase in mortgage interest rates	700,000			700,000
Dollar decrease in fair value, net of economic hedge, of mortgage servicing rights due to 50 basis point decrease in mortgage interest rates	7,100,000			7,100,000
Loans Sold Under Repurchase Agreement [Abstract]
Carrying amount of residential mortgage loans sold and subject to repurchase agreement	274,000,000	311,000,000		274,000,000	311,000,000	289,000,000
Accrual for off-balance sheet commitments to repurchase loans sold	18,000,000	14,000,000		18,000,000	14,000,000	17,000,000
Percentage of loans sold with recourse and either more than 90 days past due or in bankruptcy or foreclosure (in hundredths)	6.00%			6.00%
Principal balance of loans sold with recourse and either 90 days or more past due or in bankruptcy or foreclosure	16,000,000			16,000,000
Percentage of loans sold with recourse and 30 to 89 days past due (in hundredths)	5.00%			5.00%
Principal balance of loans sold with recourse and 30 to 89 days past due	14,000,000			14,000,000
Percentage of purchase requests	10.00%			10.00%
Number of mortgages purchased under repurchase agreement with government sponsored entities.	2			2
Purchase price of loans purchased under repurchase agreement with government sponsored entities	361,000			361,000
Number of loans with unresolved deficiency requests	166			166
Principal balance of loans with unresolved deficiency requests	27,000,000			27,000,000
Allowance for credit losses for loan repurchase under representations and warranties	$ 2,100,000			$ 2,100,000