Investments (details) - Derivatives - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Derivatives
Net realized investment gains (losses)	[1]	$ (9)	$ 10
Futures [Member] | U.S. Treasury notes contracts [Member]
Derivatives
Notional value of open contracts		400		$ 400
Net realized investment gains (losses)		$ (19)	$ (10)

[1] Total other-than-temporary impairment (OTTI) losses were $(28) million and $(4) million for the three months ended March 31, 2016 and 2015, respectively. Of total OTTI, credit losses of $(18) million and $(3) million for the three months ended March 31, 2016 and 2015, respectively, were recognized in net realized investment gains (losses). In addition, unrealized losses from other changes in total OTTI of $(10) million and $(1) million for the three months ended March 31, 2016 and 2015, 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.