Income Tax (Reconciliation of Income Tax Provision between US Statutory Rate and As Reported for Continuing Operations) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income tax expense benefit continuing operations income tax reconciliation
Tax provision at U.S. statutory rate			$ 1,706	$ 1,455	$ 1,427
Dividend received deduction			(40)	(34)	(37)
Tax-exempt income			(36)	(45)	(64)
Prior year tax (1), (2)			(127)	(27)	(179)
Low income housing tax credits			(178)	(202)	(254)
Other tax credits			(46)	(45)	(52)
Foreign tax rate differential expense (benefit)			267	414	395
Change in valuation allowance			1	(5)	(22)
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount			(4)	2	2
Deferred Federal Income Tax Expense (Benefit)			837	(115)	(235)
Provision for income tax expense (benefit)			1,551	1,509	886
MetLife Hong Kong
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential expense (benefit)					61
Provision for income tax expense (benefit)					40
MetLife Seguros de Retiro [Member]
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential expense (benefit)				60
MetLife Russia [Member]
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential expense (benefit)				24
MetLife Poland and Greece
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential expense (benefit)			50
Metropolitan Property And Casualty Insurance Company [Member]
Income tax expense benefit continuing operations income tax reconciliation
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount			(54)
MetLife Seguros S.A
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential expense (benefit)			41
Impact of U.S. Tax Reform
Income tax expense benefit continuing operations income tax reconciliation
Other Adjustments, Amount			0	0	(326)
Alternative Minimum Tax Credits
Income tax expense benefit continuing operations income tax reconciliation
Deferred Federal Income Tax Expense (Benefit)					(9)
Settlement with Taxing Authority
Income tax expense benefit continuing operations income tax reconciliation
Prior year tax (1), (2)			(117)	(40)	(158)
Provision for income tax expense (benefit)	$ (53)	$ (158)
GILTI [Member]
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential expense (benefit)			30	$ 43
GILTI [Member] | Tax Year 2020
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential expense (benefit)			(12)
GILTI [Member] | Tax Year 2021
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential expense (benefit)			42
GILTI [Member] | Impact of U.S. Tax Reform
Income tax expense benefit continuing operations income tax reconciliation
Effective Income Tax Rate Reconciliation, Tax Contingency, Foreign, Amount					12
Provision for income tax expense (benefit)					35
Foreign Tax Authority | Impact of U.S. Tax Reform
Income tax expense benefit continuing operations income tax reconciliation
Repatriation of Foreign Earnings					317
UNITED KINGDOM
Income tax expense benefit continuing operations income tax reconciliation
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount			$ 53
Change in Accounting Method Accounted for as Change in Estimate [Member] | GILTI [Member] | Impact of U.S. Tax Reform
Income tax expense benefit continuing operations income tax reconciliation
Provision for income tax expense (benefit)					$ (23)