Investments (Activity related to the pretax fixed maturity credit loss component reflected within retained earnings for securities still held for which a portion of an OTTI loss was recognized in OCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance of credit losses on fixed maturity securities	$ 53	$ 62	$ 74
Reductions for securities sold during the period	(16)	(9)	(9)
Reductions for securities the Company intends to sell or more likely than not will be required to sell	(1)	0	(3)
Ending balance of credit losses on fixed maturity securities	$ 36	$ 53	$ 62