Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ 11,631	$ 2,854	$ 1,722	$ 7,427
OCI before reclassifications	4,318	(2,357)	17,300	(9,893)
Deferred income tax benefit (expense)	(971)	402	(3,922)	2,051
AOCI before reclassifications, net of income tax	14,978	899	15,100	(415)
Amounts reclassified from AOCI	282	5	96	500
Deferred income tax benefit (expense)	(63)	96	(20)	(89)
Amounts reclassified from AOCI, net of income tax	219	101	76	411
Balance, end of period	15,197	1,000	15,197	1,000
Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	16,340	8,538	7,042	12,757
OCI before reclassifications	4,064	(1,953)	16,263	(8,860)
Deferred income tax benefit (expense)	(829)	436	(3,634)	1,977
AOCI before reclassifications, net of income tax	19,575	7,021	19,671	5,874
Amounts reclassified from AOCI	(84)	(30)	(213)	98
Deferred income tax benefit (expense)	18	7	48	(22)
Amounts reclassified from AOCI, net of income tax	(66)	(23)	(165)	76
Balance, end of period	19,509	6,998	19,509	6,998
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	2,041	1,165	1,613	905
OCI before reclassifications	658	(295)	1,305	(506)
Deferred income tax benefit (expense)	(140)	(22)	(287)	77
AOCI before reclassifications, net of income tax	2,559	848	2,631	476
Amounts reclassified from AOCI	337	4	221	309
Deferred income tax benefit (expense)	(75)	96	(49)	(47)
Amounts reclassified from AOCI, net of income tax	262	100	172	262
Balance, end of period	2,821	948	2,821	948
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(4,766)	(4,670)	(4,905)	(4,390)
OCI before reclassifications	(404)	(240)	(266)	(657)
Deferred income tax benefit (expense)	(2)	15	(1)	24
AOCI before reclassifications, net of income tax	(5,172)	(4,895)	(5,172)	(5,023)
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	(5,172)	(4,895)	(5,172)	(4,895)
Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(1,984)	(2,179)	(2,028)	(1,845)
OCI before reclassifications	0	131	(2)	130
Deferred income tax benefit (expense)	0	(27)	0	(27)
AOCI before reclassifications, net of income tax	(1,984)	(2,075)	(2,030)	(1,742)
Amounts reclassified from AOCI	29	31	88	93
Deferred income tax benefit (expense)	(6)	(7)	(19)	(20)
Amounts reclassified from AOCI, net of income tax	23	24	69	73
Balance, end of period	$ (1,961)	$ (2,051)	(1,961)	(2,051)
Accounting Standards Update 2017-12
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			26
Deferred income tax benefit (expense)			(5)
Amounts reclassified from AOCI, net of income tax			21
Accounting Standards Update 2017-12 | Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			4
Deferred income tax benefit (expense)			(1)
Amounts reclassified from AOCI, net of income tax			3
Accounting Standards Update 2017-12 | Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			22
Deferred income tax benefit (expense)			(4)
Amounts reclassified from AOCI, net of income tax			18
Accounting Standards Update 2017-12 | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			0
Deferred income tax benefit (expense)			0
Amounts reclassified from AOCI, net of income tax			0
Accounting Standards Update 2017-12 | Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI			0
Deferred income tax benefit (expense)			0
Amounts reclassified from AOCI, net of income tax			$ 0
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				92
MetLife Afore | Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI				0
MetLife Afore | Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI				0
MetLife Afore | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI				92
MetLife Afore | Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI				$ 0