Invested Assets and Related Income (Details 8) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Realized investment gains and losses [Abstract]
Fixed maturities, Gross realized gains	$ 70	$ 98	$ 110
Fixed maturities, Gross realized losses	(39)	(26)	(38)
Fixed maturities, Other-than-temporary impairment losses	(1)	(5)	(23)
Total fixed maturities	30	67	49
Equity securities, Gross realized gains	74	50	84
Equity securities, Gross realized losses	(1)	(1)	0
Equity securities, Other-than-temporary impairment losses	(22)	(6)	(89)
Total equity securities	51	43	(5)
Other invested assets	207	316	(21)
Total Realized Investment Gains, Net	$ 288	$ 426	$ 23