Equity (Statutory Net Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Metropolitan Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	$ 3,392	$ 3,859	$ 3,656
Statutory capital and surplus	11,312	10,915
American Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	980	1,386	2,086
Statutory capital and surplus	4,419	4,970
Metropolitan Property and Casualty Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	336	245	345
Statutory capital and surplus	2,249	2,159
Metropolitan Tower Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	(237)	(13)	76
Statutory capital and surplus	1,387	1,502
Other
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	84	12	$ 16
Statutory capital and surplus	$ 186	$ 105