Condensed Financial Information (Parent Company) (Support Agreements - Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Derivative Assets, Fair Value, Net	$ 8,626	$ 12,284
Unsecured derivative liability positions guaranteed by MetLife, Inc.	4,290	6,878
Derivative Liability, Fair Value, Amount Offset Against Collateral	57	38
Parent Company | Support Agreement Exeter Obligations [Member]
Condensed Financial Statements, Captions [Line Items]
Amount guaranteed under support agreement	$ 1,000
Parent Company | Support Agreement MetLife Reinsurance Company of Vermont [Member]
Condensed Financial Statements, Captions [Line Items]
Guaranteed adjusted capital levels	equal to or greater than 200% of authorized control level risk-based capital
Parent Company | Support Agreement MetLife Reinsurance Company of Charleston [Member]
Condensed Financial Statements, Captions [Line Items]
Guaranteed adjusted capital levels	equal to or greater than 200% of the company action level risk-based capital
Parent Company | Support Agreement - Guarantees of Subsidiary Derivative Obligations [Member]
Condensed Financial Statements, Captions [Line Items]
Derivative Assets, Fair Value, Net	$ 515	495
Unsecured derivative liability positions guaranteed by MetLife, Inc.	126	237
Estimated fair value of collateral provided to counterparties by the subsidiaries	114	233
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 12	$ 4