Disposition of Joint-stock Company MetLife Insurance Company (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Sale of Business		$ 158	$ 709	$ 150	$ 4,401	$ 588	$ 2,190	$ 1,746	$ 1,385	$ 5,418	$ 5,909	$ 5,128
Disposal Group, Including Discontinued Operation, Assets	$ 7,418	7,418				$ 0				7,418	$ 0	$ 0
Joint-stock Company MetLife Insurance Company [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Sale of Business	133
Disposal Group, Including Discontinued Operation, Assets	$ 382	$ 382								$ 382