Investments and Cash - Distribution of Fixed-Maturity Securities by Contractual Maturity (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Amortized Cost
Due within one year	$ 301
Due after one year through five years	1,767
Due after five years through 10 years	2,375
Due after 10 years	3,448
Estimated Fair Value
Due within one year	304
Due after one year through five years	1,843
Due after five years through 10 years	2,481
Due after 10 years	3,625
Estimated fair value	10,094		9,711
Fixed maturity securities held under trust for the benefit of reinsured companies	397		377
Eligible securities deposited for the benefit of policyholders	19		19
Fair market value of company's pledged securities	669		677
RMBS
Amortized Cost
Amortized cost	1,182
Estimated Fair Value
Estimated fair value	1,171
CMBS
Amortized Cost
Amortized cost	656
Estimated Fair Value
Estimated fair value	670
Fixed maturity securities
Amortized Cost
Amortized cost	9,729	[1]	9,488	[1]
Estimated Fair Value
Estimated fair value	$ 10,094

[1] Ratings in the tables above represent the lower of the Moody’s and S&P classifications except for bonds purchased for loss mitigation or risk management strategies, which use internal ratings classifications. The Company’s portfolio consists primarily of high-quality, liquid instruments.