Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Investments with no other-than-temporary impairment, tax provision (benefit)	$ (14)	$ 17	$ 48	$ (36)
Investments with other-than-temporary impairment, tax provision (benefit)	8	(9)	(5)	(12)
Reclassification adjustment for gains (losses) included in net income (loss), tax provision (benefit)	$ (1)	$ (6)	$ (1)	$ (4)