Investments (Net Investment Gains Losses - Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Sale of Debt Investments	$ 328	$ 251	$ 318
Non-investment portfolio gains (losses)	113	130	(1)
Gain (Loss) on Sales of Loans, Net	14	(231)	(93)
Gain (Loss) on Disposition of Other Assets	(1,162)	471	69
Gains (losses) from foreign currency transactions	(6)	225	$ 57
Brighthouse Financial, Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Sale of Debt Investments	276
Gain (Loss) on Sales of Loans, Net	47
Gain (Loss) on Disposition of Other Assets	1,016
MetLife U.S. Retail Advisor Force [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Other Assets		$ 102
MetLife Afore [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Other Assets	98
FVO Common Stock [Member] | Brighthouse Financial, Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Disposition of Other Assets	$ 95