Investments and Cash - Fixed Maturity Securities and Short Term Investments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Investments
Percent of Total	100.00%	[1]	100.00%	[1]
Amortized Cost, total investment portfolio	$ 10,392		$ 10,163
Gross Unrealized Gains, total investment portfolio	370		808
Gross Unrealized Losses, total investment portfolio	(147)		(98)
Estimated Fair Value, total investment portfolio	10,615		10,873
AOCI Gain (Loss) on Securities with OTTI	(37)	[2]	(7)
Percentage of mortgage backed securities representing government-agency obligations	50.00%		61.00%
Fixed maturity securities
Investments
Percent of Total	91.00%	[1]	92.00%	[1]
Amortized Cost Basis, fixed maturity securities	9,488		9,346
Gross Unrealized Gains, fixed maturity securities	370		808
Gross Unrealized Losses, fixed maturity securities	(147)		(98)
Estimated Fair Value, fixed maturity securities	9,711		10,056
AOCI Gain (Loss) on Securities with OTTI	(37)	[2]	(7)
Obligations of state and political subdivisions
Investments
Percent of Total	47.00%	[1]	51.00%	[1]
Amortized Cost Basis, fixed maturity securities	4,899		5,153
Gross Unrealized Gains, fixed maturity securities	219		489
Gross Unrealized Losses, fixed maturity securities	(39)		(11)
Estimated Fair Value, fixed maturity securities	5,079		5,631
AOCI Gain (Loss) on Securities with OTTI	4	[2]	9
U.S. government and agencies
Investments
Percent of Total	7.00%	[1]	7.00%	[1]
Amortized Cost Basis, fixed maturity securities	674		732
Gross Unrealized Gains, fixed maturity securities	32		62
Gross Unrealized Losses, fixed maturity securities	(6)		0
Estimated Fair Value, fixed maturity securities	700		794
AOCI Gain (Loss) on Securities with OTTI	0	[2]	0
Corporate securities
Investments
Percent of Total	13.00%	[1]	9.00%	[1]
Amortized Cost Basis, fixed maturity securities	1,314		930
Gross Unrealized Gains, fixed maturity securities	44		80
Gross Unrealized Losses, fixed maturity securities	(18)		0
Estimated Fair Value, fixed maturity securities	1,340		1,010
AOCI Gain (Loss) on Securities with OTTI	0	[2]	0
RMBS
Investments
Percent of Total	11.00%	[1],[3]	13.00%	[1],[3]
Amortized Cost Basis, fixed maturity securities	1,160	[3]	1,281	[3]
Gross Unrealized Gains, fixed maturity securities	34	[3]	62	[3]
Gross Unrealized Losses, fixed maturity securities	(72)	[3]	(77)	[3]
Estimated Fair Value, fixed maturity securities	1,122	[3]	1,266	[3]
AOCI Gain (Loss) on Securities with OTTI	(43)	[2],[3]	(59)	[3]
CMBS
Investments
Percent of Total	5.00%	[1],[3]	5.00%	[1],[3]
Amortized Cost Basis, fixed maturity securities	536	[3]	482	[3]
Gross Unrealized Gains, fixed maturity securities	17	[3]	38	[3]
Gross Unrealized Losses, fixed maturity securities	(4)	[3]	0	[3]
Estimated Fair Value, fixed maturity securities	549	[3]	520	[3]
AOCI Gain (Loss) on Securities with OTTI	0	[2],[3]	0	[3]
Asset-backed securities
Investments
Percent of Total	6.00%	[1]	5.00%	[1]
Amortized Cost Basis, fixed maturity securities	605		482
Gross Unrealized Gains, fixed maturity securities	10		59
Gross Unrealized Losses, fixed maturity securities	(7)		(10)
Estimated Fair Value, fixed maturity securities	608		531
AOCI Gain (Loss) on Securities with OTTI	2	[2]	43
Foreign government securities
Investments
Percent of Total	3.00%	[1]	2.00%	[1]
Amortized Cost Basis, fixed maturity securities	300		286
Gross Unrealized Gains, fixed maturity securities	14		18
Gross Unrealized Losses, fixed maturity securities	(1)		0
Estimated Fair Value, fixed maturity securities	313		304
AOCI Gain (Loss) on Securities with OTTI	0	[2]	0
Short-term investments
Investments
Percent of Total	9.00%	[1]	8.00%	[1]
Amortized Cost, total investment portfolio	904		817
Gross Unrealized Gains, total investment portfolio	0		0
Gross Unrealized Losses, total investment portfolio	0		0
Estimated Fair Value, total investment portfolio	904		817
AOCI Gain (Loss) on Securities with OTTI	$ 0	[2]	$ 0

[1] Based on amortized cost.

[2] Accumulated OCI ("AOCI").

[3] Government-agency obligations were approximately 50% of mortgage backed securities as of December 31, 2013 and 61% as of December 31, 2012 based on fair value.