Mortgage Banking Activities, Loans Sold With Recourse (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Activity in the allowance for losses on loans sold with recourse [Roll forward]
Beginning balance	$ 18,683,000	$ 16,667,000
Provision for recourse losses	1,672,000	794,000
Loans charged off, net	(1,704,000)	(974,000)
Ending balance	18,651,000	16,487,000
Loans Sold Under Repurchase Agreement [Abstract]
Carrying amount of residential mortgage loans sold and subject to repurchase agreement	248,000,000	284,000,000	259,000,000
Accrual for off-balance sheet commitments to repurchase loans sold	19,000,000	16,000,000	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%
Principal balance of loans sold with recourse and either 90 days or more past due or in bankruptcy or foreclosure	12,000,000
Percentage of loans sold with recourse and 30 to 89 days past due (in hundredths)	4.00%
Principal balance of loans sold with recourse and 30 to 89 days past due	11,000,000
Number of loans with unresolved deficiency requests	280		247
Principal balance of loans with unresolved deficiency requests	36,000,000		37,000,000
Number of mortgages purchased under repurchase agreement with government sponsored entities.	15	2
Purchase price of loans purchased under repurchase agreement with government sponsored entities	2,000,000	267,000
Allowance for credit losses for loan repurchase under representations and warranties	$ 2,100,000	$ 2,100,000	$ 2,200,000