Equity (Statutory Net Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Metropolitan Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	$ 3,859	$ 3,656	$ 1,982
Statutory capital and surplus	10,915	11,098
American Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	1,386	2,086	3,077
Statutory capital and surplus	4,970	4,921
Metropolitan Property and Casualty Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	245	345	197
Statutory capital and surplus	2,159	2,322
Metropolitan Tower Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	(13)	76	164
Statutory capital and surplus	1,502	1,549
Other
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	12	16	$ 11
Statutory capital and surplus	$ 105	$ 106