Dispositions - Separation of Brighthouse (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 04, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Common Stock, Shares, Issued	1,168,710,101				1,164,029,985				1,168,710,101	1,164,029,985
Common Stock, Shares Authorized	3,000,000,000				3,000,000,000				3,000,000,000	3,000,000,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									$ (986)	$ (2,734)	$ 1,324
Discontinued Operation, Separation Costs									470	212
Income (loss) from continuing operations before provision for income tax									3,536	4,281	5,651
Policyholder benefits and claims									38,313	36,358	35,144
Other expenses									13,621	13,749	14,777
Income Tax Expense (Benefit)									(1,470)	693	1,590
Income (loss) from discontinued operations, net of income tax	$ 0	$ (968)	$ 58	$ (76)	$ (1,370)	$ (435)	$ (1,361)	$ 432	(986)	(2,734)	1,324
Net investment gains (losses)									(308)	317	609
Goodwill impairment									0	260	0
Brighthouse Financial, Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax									(1,171)	0	0
Income (loss) from discontinued operations, net of income tax									$ (986)	(2,734)	$ 1,324
Common Stock, Shares, Owned by MetLife, INC.	22,996,436								22,996,436
Discontinued Operation, Equity Method Investment Retained after Disposal, Ownership Interest after Disposal									19.20%
Equity Method Investment, Quoted Market Value	$ 1,300								$ 1,300
Net investment gains (losses)									(1,016)
Gain (loss) in equity investment value									(95)
Goodwill impairment										260
Goodwill, Impairment Loss, Net of Tax										$ 223
Impact of Separation [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax									(1,302)
Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation									42
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									(1,016)
Realized intercompany gains upon Separation									61
Discontinued Operation, Tax separation agreement Expense									1,093
Discontinued Operation, Tax Benefit from Provision for (Gain) Loss on Disposal									1,051
Discontinued Operation, Separation Costs									306
Income (loss) from continuing operations before provision for income tax									(131)
Realized Investment Gains (Losses)									(693)
Policyholder benefits and claims									147
Other expenses									218
Income Tax Expense (Benefit)									(927)
Income (loss) from discontinued operations, net of income tax									(1,171)
Discontinued Operation, Other fees and costs required									$ 333
Impact of Separation [Member] | Brighthouse Financial, Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Common Stock, Shares, Issued												96,776,670
Common Stock, Shares Authorized												119,773,106
BHF Common Stock												80.80%