Insurance (Obligations Under Funding Agreements - Narrative) (Details) - USD ($) $ in Billions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Insurance [Abstract]
Funding agreements issued to certain SPEs	$ 48.5	$ 40.8	$ 40.4
Funding agreements repaid to certain SPEs	47.4	41.2	$ 36.7
Outstanding funding agreements to certain SPEs	$ 40.7	$ 39.5

Amount of funding agreements issued during current year to certain special purpose entities that have issued debt securities for which payment of interest and principal is secured by such funding agreements.

No definition available.

Name:	met_FundingAgreementsIssuedToCertainSpecialPurposeEntities
Namespace Prefix:	met_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration