Mortgage Loans Narratives (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Mortgage Loans on Real Estate [Abstract]
Carrying value of loans redesignated from HFI to HFS	$ 1,300,000,000	$ 33,000,000	$ 561,000,000
Average term extension of a single-family modified loan	154 months	131 months
Average interest rate reduction of a single-family modified loan	1.68%	2.15%
Sale of loans, unpaid principal balance	$ 1,200,000,000