Condensed Financial Information (Parent Company) Condensed Financial Information (Parent Company) (Condensed Statements of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Net cash provided by (used in) operating activities	$ 3,621	$ 3,946	$ 4,131
Cash flows from investing activities
Sales, maturities and repayments of fixed maturity securities	15,621	16,409	45,460
Sales, maturities and repayments of equity securities	22	97	224
Sales, maturities and repayments of mortgage loans	793	761	1,560
Sales, maturities and repayments of real estate joint ventures	87	77	446
Sales, maturities and repayments of other limited partnership interests	187	262	417
Purchases of fixed maturity securities	(16,427)	(17,811)	(39,097)
Purchases of equity securities	(2)	(2)	(58)
Purchases of mortgage loans	(3,890)	(2,044)	(2,847)
Purchases of real estate joint ventures	(31)	(268)	(75)
Purchases of other limited partnership interests	(327)	(263)	(203)
Cash received in connection with freestanding derivatives	1,802	1,859	707
Cash paid in connection with freestanding derivatives	(2,938)	(3,829)	(2,764)
Sale of operating joint venture interest to a former affiliate	0	42	0
Net change in policy loans	105	(14)	109
Net change in short-term investments	269	1,057	596
Net change in other invested assets	(17)	(16)	7
Net cash provided by (used in) investing activities	(4,748)	(3,683)	4,532
Cash flows from financing activities
Policyholder account balances: Deposits	5,899	4,381	10,040
Policyholder account balances: Withdrawals	(3,400)	(3,114)	(12,292)
Net change in payables for collateral under securities loaned and other transactions	889	(3,139)	(3,251)
Long-term debt issued	228	0	0
Capital contributions	0	1,300	1,688
Capital contribution associated with the sale of operating joint venture interest to a former affiliate	0	202	0
Dividends paid to MetLife, Inc.	0	0	(261)
Financing element on certain derivative instruments and other derivative related transactions, net	(303)	(149)	(1,011)
Other, net	(46)	0	0
Net cash provided by (used in) financing activities	3,258	(3,957)	(5,113)
Change in cash, cash equivalents and restricted cash	2,131	(3,694)	3,550
Cash, cash equivalents and restricted cash, beginning of year	1,363	5,057	1,507
Cash, cash equivalents and restricted cash, end of year	3,494	1,363	5,057
Supplemental disclosures of cash flow information
Net cash paid (received) for interest	3	81	130
Net cash paid (received) for income tax	(891)	(684)	150
Non-cash transactions:
Transfer of fixed maturity securities from affiliate	0	0	4,030
Transfer of mortgage loans from former affiliates	0	0	662
Transfer of short-term investments from former affiliates	0	0	94
Transfer of fixed maturity securities to former affiliates	0	293	346
Reduction of other invested assets in connection with affiliated reinsurance transactions	0	0	676
Reduction of policyholder account balances in connection with reinsurance transactions	0	293	0
Parent Company
Statement of Cash Flows [Abstract]
Net cash provided by (used in) operating activities	2,774	3,460	3,256
Cash flows from investing activities
Sales, maturities and repayments of fixed maturity securities	14,909	14,667	39,104
Sales, maturities and repayments of equity securities	19	119	175
Sales, maturities and repayments of mortgage loans	840	704	1,484
Sales, maturities and repayments of real estate joint ventures	67	75	441
Sales, maturities and repayments of other limited partnership interests	187	258	413
Purchases of fixed maturity securities	(14,697)	(16,287)	(34,906)
Purchases of equity securities	(2)	(2)	(58)
Purchases of mortgage loans	(3,896)	(2,017)	(2,803)
Purchases of real estate joint ventures	(31)	(268)	(75)
Purchases of other limited partnership interests	(327)	(263)	(203)
Cash received in connection with freestanding derivatives	1,795	1,858	707
Cash paid in connection with freestanding derivatives	(2,879)	(3,829)	(2,764)
Sale of operating joint venture interest to a former affiliate	0	67	0
Returns of capital from subsidiaries	25	7	32
Capital contributions to subsidiaries	0	(83)	(1)
Dividends from subsidiaries	0	544	0
Net change in policy loans	105	(14)	109
Net change in short-term investments	269	711	876
Net change in other invested assets	44	(41)	5
Net cash provided by (used in) investing activities	(3,572)	(3,794)	2,536
Cash flows from financing activities
Policyholder account balances: Deposits	5,064	3,845	9,672
Policyholder account balances: Withdrawals	(3,124)	(2,360)	(12,001)
Net change in payables for collateral under securities loaned and other transactions	871	(3,136)	(3,257)
Long-term debt issued	228	0	0
Capital contributions	0	1,300	1,568
Capital contribution associated with the sale of operating joint venture interest to a former affiliate	0	202	0
Dividends paid to MetLife, Inc.	0	0	(261)
Financing element on certain derivative instruments and other derivative related transactions, net	(303)	(149)	(1,011)
Other, net	(2)	0	0
Net cash provided by (used in) financing activities	2,734	(298)	(5,290)
Change in cash, cash equivalents and restricted cash	1,936	(632)	502
Cash, cash equivalents and restricted cash, beginning of year	1,249	1,881	1,379
Cash, cash equivalents and restricted cash, end of year	3,185	1,249	1,881
Supplemental disclosures of cash flow information
Net cash paid (received) for interest	0	12	64
Net cash paid (received) for income tax	(168)	(421)	428
Non-cash transactions:
Capital contributions	0	0	43
Transfer of fixed maturity securities from affiliate	417	0	0
Reduction of other invested assets in connection with affiliated reinsurance transactions	0	0	676
Reduction of policyholder account balances in connection with reinsurance transactions	0	293	0
Parent Company | MetLife, Inc.
Non-cash transactions:
Transfer of fixed maturity securities from affiliate	0	0	3,565
Transfer of mortgage loans from former affiliates	0	0	395
Transfer of short-term investments from former affiliates	0	0	94
Transfer of fixed maturity securities to former affiliates	$ 0	$ 293	$ 346