Dispositions - Disposition of MetLife Hong Kong (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	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
Net investment gains (losses)									(110)	444	(298)
Goodwill, Written off Related to Sale of Business Unit										71
Provision for income tax expense (benefit)									1,509	886	1,179
Disposal Group, Including Discontinued Operation, Assets	7,418				0				7,418	0	$ 0
MetLife Hong Kong
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Sale of Business									11	(140)
Net investment gains (losses)										(100)
Goodwill, Written off Related to Sale of Business Unit										71
Provision for income tax expense (benefit)										40
Disposal Group, Including Discontinued Operation, Assets					$ 2,900					$ 2,900
Total Loss on Sale of Business	$ 129								$ 129