Investments (Credit Loss Rollforward) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance, beginning of period	$ 378	$ 392
Additions:
Initial impairments - credit loss OTTI recognized on securities not previously impaired	0	1
Additional impairments - credit loss OTTI recognized on securities previously impaired	2	35
Reductions:
Due to sales (maturities, pay downs or prepayments) during the period of securities previously credit loss OTTI impaired	(10)	(30)
Balance, end of period	$ 370	$ 398