Guarantees Mortgage Loans Repurchase Reserve Rollforward (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Guarantees [Abstract]
Reserve For Mortgage Loan Repurchase Losses	$ 82	$ 83	$ 85	$ 78
Mortgage Repurchase Reserve, Provision for Mortgage Loan Repurchase Losses	(2)	5
Charge Offs For Mortgage Loan Repurchase Losses	$ 1	$ 0