Equity (Statutory Net Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Metropolitan Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	$ 1,982	$ 3,444	$ 3,703
Statutory capital and surplus	10,384	11,195
American Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	3,077	341	335
Statutory capital and surplus	6,548	5,895
Brighthouse Life Insurance Company [Member]
Statutory Accounting Practices [Line Items]
Statutory net income (loss)		1,186	(1,022)
Statutory capital and surplus		4,374
Metropolitan Property and Casualty Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	197	171	204
Statutory capital and surplus	2,266	2,271
Metropolitan Tower Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	74	8	(42)
Statutory capital and surplus	733	669
New England Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)		109	157
Statutory capital and surplus		455
General American Life Insurance Company
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	90	(2)	204
Statutory capital and surplus	988	923
Other
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	11	(70)	20
Statutory capital and surplus	$ 100	303
Brighthouse Financial, Inc [Member]
Statutory Accounting Practices [Line Items]
Statutory net income (loss)		(87)	$ 17
Statutory capital and surplus		$ 196