Fair Value (Fair Value Option Gains Losses for Residential Mortgage Loans - FVO) (Details) (Residential Mortgage Loans - FVO [Member], Net Investment Income [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Residential Mortgage Loans - FVO [Member] | Net Investment Income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Instrument-specific credit risk based on changes in credit spreads for non-agency loans and adjustments in individual loan quality	$ 0	$ 0	$ 0	$ 0
Other changes in estimated fair value	(2)	0	(2)	0
Total gains (losses) recognized	$ (2)	$ 0	$ (2)	$ 0