Document and Entity Information - USD ($) $ in Billions	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	METLIFE INC
Entity Central Index Key	0001099219
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 52.1
Entity Common Stock, Shares Outstanding		986,838,252