Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ 6,911	$ 5,634	$ 1,722	$ 7,427
OCI before reclassifications	6,307	(3,921)	12,982	(7,536)
Deferred income tax benefit (expense)	(1,435)	752	(2,951)	1,649
AOCI before reclassifications, net of income tax	11,783	2,465	11,753	1,540
Amounts reclassified from AOCI	(189)	584	(186)	495
Deferred income tax benefit (expense)	37	(195)	43	(185)
Amounts reclassified from AOCI, net of income tax	(152)	389	(143)	310
Balance, end of period	11,631	2,854	11,631	2,854
Unrealized Investment Gains (Losses), Net of Related Offsets
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	12,248	10,864	7,042	12,757
OCI before reclassifications	5,478	(3,096)	12,199	(6,907)
Deferred income tax benefit (expense)	(1,289)	706	(2,805)	1,541
AOCI before reclassifications, net of income tax	16,437	8,474	16,436	7,391
Amounts reclassified from AOCI	(127)	83	(129)	128
Deferred income tax benefit (expense)	30	(19)	30	(29)
Amounts reclassified from AOCI, net of income tax	(97)	64	(99)	99
Balance, end of period	16,340	8,538	16,340	8,538
Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	1,614	683	1,613	905
OCI before reclassifications	658	141	647	(211)
Deferred income tax benefit (expense)	(153)	41	(147)	99
AOCI before reclassifications, net of income tax	2,119	865	2,113	793
Amounts reclassified from AOCI	(92)	470	(116)	305
Deferred income tax benefit (expense)	14	(170)	26	(143)
Amounts reclassified from AOCI, net of income tax	(78)	300	(90)	162
Balance, end of period	2,041	1,165	2,041	1,165
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(4,947)	(3,707)	(4,905)	(4,390)
OCI before reclassifications	174	(969)	138	(417)
Deferred income tax benefit (expense)	7	6	1	9
AOCI before reclassifications, net of income tax	(4,766)	(4,670)	(4,766)	(4,798)
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	(4,766)	(4,670)	(4,766)	(4,670)
Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(2,004)	(2,206)	(2,028)	(1,845)
OCI before reclassifications	(3)	3	(2)	(1)
Deferred income tax benefit (expense)	0	(1)	0	0
AOCI before reclassifications, net of income tax	(2,007)	(2,204)	(2,030)	(1,846)
Amounts reclassified from AOCI	30	31	59	62
Deferred income tax benefit (expense)	(7)	(6)	(13)	(13)
Amounts reclassified from AOCI, net of income tax	23	25	46	49
Balance, end of period	$ (1,984)	$ (2,179)	(1,984)	(2,179)
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