Mortgage Servicing Rights (Details) (Mortgage Servicing Rights, USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Mortgage Servicing Rights
Mortgage Servicing Rights
Residential mortgage loans serviced for third parties	$ 3,100,000,000		$ 3,100,000,000
Servicing income, including late and ancillary fees	2,000,000	2,100,000
Change in carring value of the mortgage servicing rights accounted for under the fair value measurement method
Balance at the beginning of the Period	4,761,000	7,131,000
Change in Fair Value:
Due to Change in Valuation Assumptions	34,000	(313,000)
Due to Payoffs	(359,000)	(395,000)
Total Changes in Fair Value of Mortgage Servicing Rights	(325,000)	(708,000)
Balance at the end of the Period	$ 4,436,000	$ 6,423,000