Accumulated Other Comprehensive Income (Loss) Narrative (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pretax net unrealized gains (losses) on available-for-sale securities with OTTI losses reclassified out of AOCI and recognized in earnings	$ (28)	$ (83)	$ (42)
Tax (expense) benefit on pretax net unrealized gains (losses) on available-for-sale securities with OTTI losses reclassified out of AOCI and recognized in earnings	10	29	15
Pretax net unrealized gains (losses) on other available-for-sale securities reclassified out of AOCI and recognized in earnings	89	60	137
Tax (expense) benefit on pretax net unrealized gains (losses) on other available-for-sale securities reclassified out of AOCI and recognized in earnings	$ (31)	$ (21)	$ (48)