Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ 2,854	$ 8,436	$ 7,427	$ 5,366
OCI before reclassifications	(2,357)	832	(9,893)	5,526
Deferred income tax benefit (expense)	402	(218)	2,051	(1,572)
AOCI before reclassifications, net of income tax	899	9,050	(415)	9,320
Amounts reclassified from AOCI	5	(627)	500	(1,051)
Deferred income tax benefit (expense)	96	216	(89)	370
Amounts reclassified from AOCI, net of income tax	101	(411)	411	(681)
Balance, end of period	1,000	7,005	1,000	7,005
Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	8,538	13,469	12,757	10,785
OCI before reclassifications	(1,953)	803	(8,860)	4,796
Deferred income tax benefit (expense)	436	(270)	1,977	(1,675)
AOCI before reclassifications, net of income tax	7,021	14,002	5,874	13,906
Amounts reclassified from AOCI	(30)	(360)	98	(211)
Deferred income tax benefit (expense)	7	126	(22)	73
Amounts reclassified from AOCI, net of income tax	(23)	(234)	76	(138)
Balance, end of period	6,998	12,282	6,998	12,282
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	1,165	1,569	905	1,865
OCI before reclassifications	(295)	(166)	(506)	37
Deferred income tax benefit (expense)	(22)	56	77	(14)
AOCI before reclassifications, net of income tax	848	1,459	476	1,888
Amounts reclassified from AOCI	4	(307)	309	(965)
Deferred income tax benefit (expense)	96	107	(47)	336
Amounts reclassified from AOCI, net of income tax	100	(200)	262	(629)
Balance, end of period	948	1,061	948	1,061
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(4,670)	(4,679)	(4,390)	(5,312)
OCI before reclassifications	(240)	193	(657)	710
Deferred income tax benefit (expense)	15	(6)	24	110
AOCI before reclassifications, net of income tax	(4,895)	(4,492)	(5,023)	(4,492)
Amounts reclassified from AOCI	0	0	0	0
Deferred income tax benefit (expense)	0	0	0	0
Amounts reclassified from AOCI, net of income tax	0	0	0	0
Balance, end of period	(4,895)	(4,460)	(4,895)	(4,460)
Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(2,179)	(1,923)	(1,845)	(1,972)
OCI before reclassifications	131	2	130	(17)
Deferred income tax benefit (expense)	(27)	2	(27)	7
AOCI before reclassifications, net of income tax	(2,075)	(1,919)	(1,742)	(1,982)
Amounts reclassified from AOCI	31	40	93	125
Deferred income tax benefit (expense)	(7)	(17)	(20)	(39)
Amounts reclassified from AOCI, net of income tax	24	23	73	86
Balance, end of period	$ (2,051)	(1,878)	(2,051)	(1,878)
Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			(425)
Deferred income tax benefit (expense)			1,337
Amounts reclassified from AOCI, net of income tax			912
Accounting Standards Update 2016-01 | Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			(425)
Deferred income tax benefit (expense)			1,473
Amounts reclassified from AOCI, net of income tax			1,048
Accounting Standards Update 2016-01 | Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			0
Deferred income tax benefit (expense)			210
Amounts reclassified from AOCI, net of income tax			210
Accounting Standards Update 2016-01 | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			0
Deferred income tax benefit (expense)			36
Amounts reclassified from AOCI, net of income tax			36
Accounting Standards Update 2016-01 | Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			0
Deferred income tax benefit (expense)			(382)
Amounts reclassified from AOCI, net of income tax			(382)
MetLife Afore
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI, net of income tax			92
MetLife Afore | Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI, net of income tax			0
MetLife Afore | Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI, net of income tax			0
MetLife Afore | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI, net of income tax			92
MetLife Afore | Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI, net of income tax			$ 0
Brighthouse Financial, Inc
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI		(2,512)		(2,512)
Deferred income tax benefit (expense)		878		878
Amounts reclassified from AOCI, net of income tax		(1,634)		(1,634)
Brighthouse Financial, Inc | Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI		(2,286)		(2,286)
Deferred income tax benefit (expense)		800		800
Amounts reclassified from AOCI, net of income tax		(1,486)		(1,486)
Brighthouse Financial, Inc | Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI		(305)		(305)
Deferred income tax benefit (expense)		107		107
Amounts reclassified from AOCI, net of income tax		(198)		(198)
Brighthouse Financial, Inc | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI		51		51
Deferred income tax benefit (expense)		(19)		(19)
Amounts reclassified from AOCI, net of income tax		32		32
Brighthouse Financial, Inc | Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI		28		28
Deferred income tax benefit (expense)		(10)		(10)
Amounts reclassified from AOCI, net of income tax		$ 18		$ 18