Market Risk Benefits - Transition Adjustments (Details) - USD ($) $ in Millions	Jan. 01, 2021	Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Direct and assumed MRB liabilities	$ 7,901	$ 0
Reclassification of carrying amounts of contracts and contract features that are market risk benefits	2,789
Adjustments for the cumulative effect of changes in nonperformance risk between contract issue date and Transition Date	(99)
Adjustments for the difference between the fair value of the MRB balance, excluding the cumulative effect of changes in nonperformance risk, and the historical carrying value	5,211
Reinsured MRB assets	51	0
Reclassification of carrying amounts of contracts and contract features that are market risk benefits	63
Adjustments for the difference between previous carrying amounts and fair value measurements	(12)
Insurance, Other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Direct and assumed MRB liabilities	582	0
Reclassification of carrying amounts of contracts and contract features that are market risk benefits	251
Adjustments for the cumulative effect of changes in nonperformance risk between contract issue date and Transition Date	(38)
Adjustments for the difference between the fair value of the MRB balance, excluding the cumulative effect of changes in nonperformance risk, and the historical carrying value	369
Reinsured MRB assets	51	0
Reclassification of carrying amounts of contracts and contract features that are market risk benefits	63
Adjustments for the difference between previous carrying amounts and fair value measurements	(12)
Asia
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Direct and assumed MRB liabilities	318	0
Reclassification of carrying amounts of contracts and contract features that are market risk benefits	247
Adjustments for the cumulative effect of changes in nonperformance risk between contract issue date and Transition Date	(7)
Adjustments for the difference between the fair value of the MRB balance, excluding the cumulative effect of changes in nonperformance risk, and the historical carrying value	78
Reinsured MRB assets	0	0
Reclassification of carrying amounts of contracts and contract features that are market risk benefits	0
Adjustments for the difference between previous carrying amounts and fair value measurements	0
MetLife Holdings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Direct and assumed MRB liabilities	7,001	0
Reclassification of carrying amounts of contracts and contract features that are market risk benefits	2,291
Adjustments for the cumulative effect of changes in nonperformance risk between contract issue date and Transition Date	(54)
Adjustments for the difference between the fair value of the MRB balance, excluding the cumulative effect of changes in nonperformance risk, and the historical carrying value	4,764
Reinsured MRB assets	0	$ 0
Reclassification of carrying amounts of contracts and contract features that are market risk benefits	0
Adjustments for the difference between previous carrying amounts and fair value measurements	$ 0