Investments (Credit Loss Rollforward) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance, beginning of period	$ 58	$ 56	$ 59	$ 55
Additions:
Initial impairments - credit loss OTTI recognized on securities not previously impaired	0	1	1	5
Additional impairments - credit loss OTTI recognized on securities previously impaired	5	2	12	9
Reductions:
Due to sales (maturities, pay downs or prepayments) during the period of securities previously credit loss OTTI impaired	(4)	(7)	(13)	(11)
Due to increases in cash flows- accretion of previous credit loss OTTI	0	0	0	(6)
Balance, end of period	$ 59	$ 52	$ 59	$ 52