Income Tax (Reconciliation of Income Tax Provision between US Statutory Rate and As Reported for Continuing Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income tax expense benefit continuing operations income tax reconciliation
Tax provision at U.S. statutory rate	$ (1,648)	$ 369	$ 102
Dividend received deduction	(105)	(127)	(114)
Prior year tax	23	(4)	(20)
Tax credits	(20)	(16)	(14)
Foreign tax rate differential	2	(5)	0
Goodwill impairment	(20)	0	12
Sale of subsidiary	(6)	0	24
Other, net	3	(2)	5
Provision for income tax expense (benefit)	$ (1,771)	$ 215	$ (5)