Mortgage Banking Activities, Loans Sold With Recourse (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Activity in the allowance for losses on loans sold with recourse [Roll forward]
Beginning balance	$ 17,832,000	$ 17,540,000	$ 18,683,000	$ 16,667,000
Provision for recourse losses	1,055,000	3,246,000	3,495,000	6,572,000
Loans charged off, net	(1,255,000)	(2,264,000)	(4,546,000)	(4,717,000)
Ending balance	17,632,000	18,522,000	17,632,000	18,522,000
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	2,200,000		2,200,000
Dollar decrease in fair value, net of economic hedge, of mortgage servicing rights due to 50 basis point decrease in mortgage interest rates	3,900,000		3,900,000
Loans Sold Under Repurchase Agreement [Abstract]
Carrying amount of residential mortgage loans sold and subject to repurchase agreement	238,000,000	262,000,000	238,000,000	262,000,000	259,000,000
Accrual for off-balance sheet commitments to repurchase loans sold	18,000,000	19,000,000	18,000,000	19,000,000	19,000,000
Percentage of loans sold with recourse and either more than 90 days past due or in bankruptcy or foreclosure (in hundredths)	5.00%		5.00%
Principal balance of loans sold with recourse and either 90 days or more past due or in bankruptcy or foreclosure	12,000,000		12,000,000
Percentage of loans sold with recourse and 30 to 89 days past due (in hundredths)	6.00%		6.00%
Principal balance of loans sold with recourse and 30 to 89 days past due	15,000,000		15,000,000
Number of mortgages purchased under repurchase agreement with government sponsored entities.			41
Purchase price of loans purchased under repurchase agreement with government sponsored entities	4,700,000		4,700,000
Number of loans with unresolved deficiency requests	344		344		247
Losses incurred on actual repurchased loans from governmental sponsored entities with warranties	1,500,000		1,500,000
Principal balance of loans with unresolved deficiency requests	42,000,000		42,000,000		37,000,000
Number of loans sold under standard representations and warranties indemnified			3
Principal Balance at period end of mortgage loans indemnified during period	270,000		270,000
Allowance for credit losses for loan repurchase under representations and warranties	$ 4,800,000		$ 4,800,000		$ 2,200,000