Long-term and Short-term Debt (Committed Facilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Jul. 21, 2017	Jun. 30, 2017	Apr. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Collateral financing arrangement	$ 1,121				$ 1,274
Committed Credit Facility Four [Member]
Debt Instrument [Line Items]
Borrowers	MetLife, Inc.
Expiration	Jun. 20, 2018
Line of Credit Facility, Maximum Borrowing Capacity	$ 395
Letters of Credit Issued	395
Collateral financing arrangement	0
Unused Commitments	$ 0
Committed Credit Facility Three [Member]
Debt Instrument [Line Items]
Borrowers	MetLife Reinsurance Company of Vermont and MetLife, Inc.
Expiration	Dec. 28, 2024
Line of Credit Facility, Maximum Borrowing Capacity	$ 400
Letters of Credit Issued	380
Collateral financing arrangement	0
Unused Commitments	$ 20
Committed Credit Facility Six [Member]
Debt Instrument [Line Items]
Borrowers	MetLife Reinsurance Company of Vermont and MetLife, Inc.
Expiration	Dec. 31, 2037
Line of Credit Facility, Maximum Borrowing Capacity	$ 2,896
Letters of Credit Issued	2,354
Collateral financing arrangement	0
Unused Commitments	542
Committed Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	3,691
Letters of Credit Issued	3,129
Collateral financing arrangement	0
Unused Commitments	562
Brighthouse Financial, Inc [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 600	$ 536	$ 3,000
Brighthouse Financial, Inc [Member] | Committed Credit Facility Five [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				3,500
Brighthouse Financial, Inc [Member] | Committed Credit Facility Six [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	2,900
Letters of Credit Issued	$ 2,400
Brighthouse Financial, Inc [Member] | Committed Credit Facility Seven [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 4,300