Long-term and Short-term Debt (Committed Facilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jul. 21, 2017	Jun. 30, 2017	Apr. 30, 2017
Debt Instrument [Line Items]
Collateral financing arrangement	$ 1,060	$ 1,121
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	385
Collateral financing arrangement	0
Unused Commitments	$ 15
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	2,420
Collateral financing arrangement	0
Unused Commitments	476
Committed Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	3,296
Letters of Credit Issued	2,805
Collateral financing arrangement	0
Unused Commitments	491
Brighthouse Financial, Inc
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 600	$ 536	$ 3,000
Brighthouse Financial, Inc | Committed Credit Facility Six [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	2,900
Letters of Credit Issued	$ 2,400	$ 2,400