Mortgage Banking (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Mortgage Banking [Abstract]
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	$ 1,000,000	$ (263,000)
Mortgage servicing rights [Abstract]
Balance at beginning of period	43,274,000	51,151,000
Origination of servicing assets	4,477,000	3,480,000
Change in fair value:
Due to market changes	248,000	257,000
Due to runoff	(2,106,000)	(1,290,000)
Balance at end of period	45,893,000	53,598,000
Mortgage loan servicing representation and warranty expenses incurred	1,900,000	643,000
Accrual for mortgage loan servicing representation and warranty expenses	$ 4,800,000		$ 4,300,000