Business Dispositions and Discontinued Operations - Additional Information (Details) - USD ($) $ in Millions				3 Months Ended			6 Months Ended		7 Months Ended	12 Months Ended
	May 31, 2018	Jan. 01, 2018	Dec. 03, 2017	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on discontinued operations							$ (213)	$ 0
TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect		$ (88)
Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect					$ (193)
Discontinued Operation, Tax Effect of Discontinued Operation							(133)
Cumulative effect of accounting change net of income taxes		$ 10
Discontinued Operations, Held-for-sale [Member] | Run-Off Life and Annuity Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds from sale of business	$ 1,400
Dividends paid	$ 300
Ownership interest retained, percentage	970.00%
Ownership interest retained	$ 164
Reduction in long term debt	142									$ 142
Consideration received	$ 1,500
Loss on discontinued operations									$ 3,000	3,300
Discontinued Operation, Amount of Adjustment to Prior Period Gain (Loss) on Disposal, Net of Tax				$ 151		$ 0	213	0
Disposal Group, Including Discontinued Operation, Operating Income (Loss)							104
Adjustments to AOCI										1,000
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax				(9)		$ 143	113	$ 227
Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Adjustments to AOCI				$ 758			$ 758		$ 758
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect					$ (193)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cumulative effect of accounting change net of income taxes										$ 273
Asset Management Income [Member] | Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Management agreement term			5 years
Other Income [Member] | Discontinued Operations, Held-for-sale [Member] | Minimum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Management agreement term			12 months
Other Income [Member] | Discontinued Operations, Held-for-sale [Member] | Maximum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Management agreement term			24 months