Investments (details) - Derivatives (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Derivative
Net realized investment gain (loss)	$ 1	[1]	$ 10	[1]
Futures [Member] | U.S. Treasury notes contracts [Member]
Derivative
Net realized investment gain (loss)	$ 1		$ (19)

[1] Total other-than-temporary impairment (OTTI) gains (losses) were $(7) million for the three months ended March 31, 2014 and $0 million for the three months ended March 31, 2013. Of total OTTI, credit losses of $(9) million and $(5) million for the three months ended March 31, 2014 and 2013, respectively, were recognized in net realized investment gains. In addition, unrealized gains from other changes in total OTTI of $2 million and $5 million for the three months ended March 31, 2014 and 2013, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.