Investments - Real Estate and Other Long-Term Investments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Investments [Abstract]
Carrying value of non-income producing real estate investments	$ 63	$ 49
Commitments to contribute additional equity to real estate investments	3
Other Long Term Investments [Line Items]
Other long-term investments	1,273	1,255
Carrying Value Of Non Income Producing Real Estate Entities And Securities Partnerships	154	199
Commitments to contribute to limited liability entities that hold real estate or loans to real estate	305
Commitments to contribute to entities that hold securities diversified by issuer and maturity date	338
Percentage of the committed amounts to be disbursed by the end of next year	63.00%
Real Estate Entities [Member]
Other Long Term Investments [Line Items]
Other long-term investments	812	823
Security Partnerships [Member]
Other Long Term Investments [Line Items]
Other long-term investments	357	343
Other Long Term Investments [Member]
Other Long Term Investments [Line Items]
Other long-term investments	$ 104	$ 89