Mortgage Servicing Rights - Narrative (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Mortgage Servicing Rights Disclosure [Abstract]
Residential mortgage loans serviced for third parties	$ 3,100,000,000		$ 3,100,000,000		$ 3,100,000,000
Servicing income, including late and ancillary fees	$ 2,000,000	$ 2,000,000	$ 6,000,000	$ 6,200,000