Investments (Activity related to the pretax fixed maturity credit loss component reflected within retained earnings for securities still held) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance of credit losses on fixed maturity securities	$ 99	$ 82	$ 92	$ 141
Additional credit losses for securities for which an OTTI loss was previously recognized	2	11	23	29
Credit losses for securities for which an OTTI loss was not previously recognized		10	2	11
Reductions for securities sold during the period	(3)	(4)	(11)	(50)
Reductions for securities the Company intends to sell or more likely than not will be required to sell			(8)	(32)
Ending balance of credit losses on fixed maturity securities	$ 98	$ 99	$ 98	$ 99