Investments and Cash - Net Investment Income, Net Realized Investment Gains (Losses) and Roll Forward of Credit Losses in the Investment Portfolio (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended						3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Fixed Maturities managed externally	Mar. 31, 2013 Fixed Maturities managed externally	Mar. 31, 2014 Fixed and short-term maturity securities	Dec. 31, 2013 Fixed and short-term maturity securities	Mar. 31, 2014 Fixed Maturities managed internally	Mar. 31, 2013 Fixed Maturities managed internally	Mar. 31, 2014 Other Invested Assets internally managed	Mar. 31, 2013 Other Invested Assets internally managed
Investments
Available-for-sale Securities, Gross Realized Gains	$ 4	$ 6
Accrued investment income					95	93
Net Investment Income
Gross investment income	105	96	80	79			20	16	5	1
Investment expenses	(2)	(2)
Net investment income	103	94
Net Realized Investment Gains (Losses)
Realized gains on investment portfolio	5	33
Available-for-sale Securities, Gross Realized Losses	(2)	(4)
Realized losses on investment portfolio	0	(2)
Other than Temporary Impairment Losses, Investments	(5)	(5)
Other-than-temporary impairment (OTTI):
Net realized investment gains (losses)	2	28
Roll Forward of Credit Losses in the Investment Portfolio
Balance, at the beginning of the period	80	64
Additions for credit losses on securities for which an OTTI was not previously recognized	1	1
Additions for credit losses on securities for which an OTTI was previously recognized	4	4
Balance, at the end of the period	$ 85	$ 69