Accumulated Other Comprehensive Income Loss - AOCI Rollforward (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
	Jan. 01, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 13,494		$ 13,494		$ 13,494
OCI, net of tax		$ (1,114)		$ 701	(2,011)	$ 831
Ending balance		12,546		17,288	12,546	17,288
TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect	(88)
Equity securities and shadow DAC [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting changes, net of tax [1]	93
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before Reclassifications, Net of Tax, Attributable to Parent		(1,148)		404	(2,030)	564
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,931	1,349	1,931	1,413	1,931	1,276
Cumulative effect of accounting changes, net of tax [1]							$ 273
Adjusted balance, beginning of period							2,204
Amounts reclassified from AOCI		10		(62)	37	(85)
OCI, net of tax		(1,138)		342	(1,993)	479
Ending balance		211	1,349	1,755	211	1,755
Accumulated Other-than-Temporary Impairment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before Reclassifications, Net of Tax, Attributable to Parent		3		1	1	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(3)	(5)	(3)	(4)	(3)	(3)
Cumulative effect of accounting changes, net of tax [1]							0
Adjusted balance, beginning of period							(3)
Amounts reclassified from AOCI		(1)		0	(1)	0
OCI, net of tax		2		1	0	0
Ending balance		(3)	(5)	(3)	(3)	(3)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before Reclassifications, Net of Tax, Attributable to Parent		18		13	(13)	8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	18	(24)	18	58	18	76
Cumulative effect of accounting changes, net of tax [1]							2
Adjusted balance, beginning of period							20
Amounts reclassified from AOCI		(6)		(14)	(19)	(27)
OCI, net of tax		12		(1)	(32)	(19)
Ending balance		(12)	(24)	57	(12)	57
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before Reclassifications, Net of Tax, Attributable to Parent		1		5	(5)	7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	34	32	34	8	34	6
Cumulative effect of accounting changes, net of tax [1]							4
Adjusted balance, beginning of period							38
Amounts reclassified from AOCI		0		0	0	0
OCI, net of tax		1		5	(5)	7
Ending balance		33	32	13	33	13
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before Reclassifications, Net of Tax, Attributable to Parent		(1)		(141)	(1)	(140)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,317)	(1,591)	(1,317)	(1,682)	(1,317)	(1,692)
Cumulative effect of accounting changes, net of tax [1]							(284)
Adjusted balance, beginning of period							(1,601)
Amounts reclassified from AOCI		10		495	20	504
OCI, net of tax		9		354	19	364
Ending balance		(1,582)	(1,591)	(1,328)	(1,582)	(1,328)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before Reclassifications, Net of Tax, Attributable to Parent		(1,127)		282	(2,048)	439
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 663	(239)	663	(207)	663	(337)
Cumulative effect of accounting changes, net of tax [1]							(5)	$ 0
Adjusted balance, beginning of period							$ 658	$ (337)
Amounts reclassified from AOCI		13		419	37	392
OCI, net of tax		(1,114)		701	(2,011)	831
Ending balance		(1,353)	$ (239)	$ 494	(1,353)	$ 494
Discontinued Operations, Disposed of by Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Disposal Group, Including Discontinued Operations, Adjustments to AOCI		$ 758			$ 758