Consolidated Supplementary Insurance Information (Income Statement Items) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	$ 49,435	$ 53,735	$ 46,396
Net Investment Income	19,908	15,916	21,395
Policyholder Benefits and Claims, Policyholder Liability Remeasurement (Gains) Losses and Interest Credited to Policyholder Account Balances	52,405	53,515	48,517
Market Risk Benefit Remeasurement (Gains) Losses	(994)	(3,674)	(1,237)
Amortization of DAC and VOBA Charged to Other Expenses	1,952	1,831	2,037
Other Expenses (1)	11,380	10,734	10,861
Group Benefits
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	22,436	21,906	21,304
Net Investment Income	1,148	1,081	1,102
Policyholder Benefits and Claims, Policyholder Liability Remeasurement (Gains) Losses and Interest Credited to Policyholder Account Balances	19,329	19,226	19,929
Market Risk Benefit Remeasurement (Gains) Losses	0	0	0
Amortization of DAC and VOBA Charged to Other Expenses	26	26	26
Other Expenses (1)	3,778	3,460	3,158
Retirement and Income Solutions
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	8,561	13,923	5,334
Net Investment Income	7,354	5,899	6,606
Policyholder Benefits and Claims, Policyholder Liability Remeasurement (Gains) Losses and Interest Credited to Policyholder Account Balances	14,057	18,124	8,928
Market Risk Benefit Remeasurement (Gains) Losses	(29)	(314)	96
Amortization of DAC and VOBA Charged to Other Expenses	49	40	37
Other Expenses (1)	403	380	368
Asia
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	6,883	7,256	8,047
Net Investment Income	4,307	3,571	5,110
Policyholder Benefits and Claims, Policyholder Liability Remeasurement (Gains) Losses and Interest Credited to Policyholder Account Balances	6,941	6,199	7,386
Market Risk Benefit Remeasurement (Gains) Losses	(43)	(90)	(48)
Amortization of DAC and VOBA Charged to Other Expenses	794	745	786
Other Expenses (1)	1,562	1,601	1,758
Latin America
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	5,685	4,399	3,749
Net Investment Income	1,610	1,318	1,207
Policyholder Benefits and Claims, Policyholder Liability Remeasurement (Gains) Losses and Interest Credited to Policyholder Account Balances	4,801	4,092	3,475
Market Risk Benefit Remeasurement (Gains) Losses	0	0	0
Amortization of DAC and VOBA Charged to Other Expenses	468	410	372
Other Expenses (1)	1,263	1,032	978
EMEA
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	2,314	2,298	2,803
Net Investment Income	885	(864)	932
Policyholder Benefits and Claims, Policyholder Liability Remeasurement (Gains) Losses and Interest Credited to Policyholder Account Balances	1,737	30	2,085
Market Risk Benefit Remeasurement (Gains) Losses	(40)	(126)	(120)
Amortization of DAC and VOBA Charged to Other Expenses	348	331	389
Other Expenses (1)	807	778	900
MetLife Holdings
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	3,513	3,968	4,256
Net Investment Income	4,234	4,633	6,093
Policyholder Benefits and Claims, Policyholder Liability Remeasurement (Gains) Losses and Interest Credited to Policyholder Account Balances	5,517	5,849	6,097
Market Risk Benefit Remeasurement (Gains) Losses	(882)	(3,144)	(1,161)
Amortization of DAC and VOBA Charged to Other Expenses	258	270	320
Other Expenses (1)	1,527	1,632	1,845
Corporate & Other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	43	(15)	903
Net Investment Income	370	278	345
Policyholder Benefits and Claims, Policyholder Liability Remeasurement (Gains) Losses and Interest Credited to Policyholder Account Balances	23	(5)	617
Market Risk Benefit Remeasurement (Gains) Losses	0	0	(4)
Amortization of DAC and VOBA Charged to Other Expenses	9	9	107
Other Expenses (1)	$ 2,040	$ 1,851	$ 1,854