Investments (Net Investment Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Investment Income [Line Items]
Gain (Loss) on Sales of Loans, Net	$ 14	$ (231)	$ (93)
Gain (Loss) on Disposition of Other Assets	(1,162)	471	69
Less: Investment expenses	1,122	972	1,082
Net Investment Income	17,363	16,790	16,205
Securities Investment
Net Investment Income [Line Items]
Subtotal	17,185	16,812	17,023
Net Investment Income	16,063	15,840	15,941
FVO contractholder-directed unit-linked investments
Net Investment Income [Line Items]
Net Investment Income	1,300	950	264
Changes in estimated fair value included in net investment income	662	427	(456)
Fixed Maturity Securities
Net Investment Income [Line Items]
Subtotal	11,497	11,721	11,809
Equity securities
Net Investment Income [Line Items]
Subtotal	129	121	124
FVO securities — FVO general account securities (1)
Net Investment Income [Line Items]
Subtotal	68	37	21
Mortgage Loans
Net Investment Income [Line Items]
Subtotal	3,082	2,858	2,772
Policy loans
Net Investment Income [Line Items]
Subtotal	517	511	525
Real estate and real estate joint ventures
Net Investment Income [Line Items]
Subtotal	646	652	872
Other limited partnership interests
Net Investment Income [Line Items]
Subtotal	798	478	535
Cash, cash equivalents and short-term investments
Net Investment Income [Line Items]
Subtotal	228	153	140
Operating joint ventures
Net Investment Income [Line Items]
Subtotal	28	33	25
Other
Net Investment Income [Line Items]
Subtotal	192	248	$ 200
Brighthouse Financial, Inc [Member]
Net Investment Income [Line Items]
Gain (Loss) on Sales of Loans, Net	47
Gain (Loss) on Disposition of Other Assets	1,016
MetLife U.S. Retail Advisor Force
Net Investment Income [Line Items]
Gain (Loss) on Disposition of Other Assets		$ 102
MetLife Afore [Member]
Net Investment Income [Line Items]
Gain (Loss) on Disposition of Other Assets	98
FVO Common Stock [Member] | Brighthouse Financial, Inc [Member]
Net Investment Income [Line Items]
Gain (Loss) on Disposition of Other Assets	$ 95