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, 2023	Dec. 31, 2022	Dec. 31, 2021
Income tax expense benefit continuing operations income tax reconciliation
Tax provision at U.S. statutory rate		$ 454	$ 1,337	$ 1,789
Dividend received deduction		(18)	(20)	(40)
Tax-exempt income		(34)	15	(36)
Prior year tax (1)		(12)	(15)	(127)
Low income housing tax credits		(116)	(143)	(178)
Other tax credits		(39)	(44)	(46)
Foreign tax rate differential (2), (3), (4)		(312)	85	(275)
Effective Income Tax Rate Reconciliation, Change In Tax Law, Amount	$ 0	(198)	0	0
Change in valuation allowance (5)		187	0	1
Other, net		(24)	(17)	(4)
Deferred Federal Income Tax Expense (Benefit)		(591)	1,234	872
Provision for income tax expense (benefit)		560	1,062	1,642
U.S. tax on global intangible low-taxes income		22	12	30
Tax Year 2020
Income tax expense benefit continuing operations income tax reconciliation
U.S. tax on global intangible low-taxes income				(12)
Tax Year 2021
Income tax expense benefit continuing operations income tax reconciliation
U.S. tax on global intangible low-taxes income			(21)	42
Tax Year 2022
Income tax expense benefit continuing operations income tax reconciliation
U.S. tax on global intangible low-taxes income		6	33
Tax Year 2023
Income tax expense benefit continuing operations income tax reconciliation
U.S. tax on global intangible low-taxes income		28
Enactment of Bermuda Corporate Income Tax
Income tax expense benefit continuing operations income tax reconciliation
Change in valuation allowance (5)		198
Provision for income tax expense (benefit)		(198)
MetLife Poland and Greece
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential (2), (3), (4)				(50)
MetLife Seguros S.A
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential (2), (3), (4)				$ (41)
MetLife Malaysia
Income tax expense benefit continuing operations income tax reconciliation
Foreign tax rate differential (2), (3), (4)		(28)
Settlement with Taxing Authority
Income tax expense benefit continuing operations income tax reconciliation
Prior year tax (1)		$ (32)	$ (117)
Provision for income tax expense (benefit)	$ (53)