Pending Disposition of MetLife Poland and Greece (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	$ 7,462		$ 0
Cash and cash equivalents	103	$ 765	0	$ 0
Liabilities held-for-sale	6,757	$ 4,650	$ 0
MetLife Poland and Greece
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	7,462
Cash and cash equivalents	103
Other	275
Liabilities held-for-sale	6,757
Other	133
MetLife Poland and Greece | Fixed Maturities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	2,143
MetLife Poland and Greece | Contractholder-directed equity securities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	1,098
MetLife Poland and Greece | Other Investments
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	136
MetLife Poland and Greece | Investments
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	3,377
MetLife Poland and Greece | Deferred policy acquisition costs
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	139
MetLife Poland and Greece | Separate Accounts
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets	3,568
MetLife Poland and Greece | Future policy benefits [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities held-for-sale	940
MetLife Poland and Greece | Policyholder Account Balances [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities held-for-sale	2,013
MetLife Poland and Greece | Other Policy-Related Balances
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities held-for-sale	103
MetLife Poland and Greece | Separate account liabilities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities held-for-sale	$ 3,568