Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues
Premiums									$ 44,283	$ 48,510	$ 41,152
Universal life and investment-type product policy fees									5,152	5,225	5,244
Net investment income									19,908	15,916	21,395
Other revenues									2,526	2,630	2,619
Net investment gains (losses)									(2,824)	(1,260)	1,543
Net derivative gains (losses)									(2,140)	(2,251)	(3,257)
Total revenues	$ 19,028	$ 15,866	$ 16,623	$ 15,388	$ 15,608	$ 22,283	$ 15,474	$ 15,405	66,905	68,770	68,696
Expenses
Policyholder benefits and claims									44,590	49,507	43,118
Policyholder liability remeasurement (gains) losses									(45)	114	(172)
Market Risk Benefit Remeasurement (Gains) Losses									(994)	(3,674)	(1,237)
Interest credited to policyholder account balances									7,860	3,894	5,571
Policyholder dividends									622	706	880
Other expenses									12,710	11,859	12,018
Total expenses	18,087	15,332	16,193	15,131	13,582	20,868	14,486	13,470	64,743	62,406	60,178
Income (loss) before provision for income tax									2,162	6,364	8,518
Provision for income tax expense (benefit)									560	1,062	1,642
Net income (loss)	614	495	408	85	1,581	1,167	915	1,639	1,602	5,302	6,876
Less: Net income (loss) attributable to noncontrolling interests	7	6	6	5	3	5	5	5	24	18	21
Net income (loss) attributable to MetLife, Inc.	607	489	402	80	1,578	1,162	910	1,634	1,578	5,284	6,855
Less: Preferred stock dividends	33	67	32	66	29	64	29	63	198	185	195
Preferred stock redemption premium									0	0	6
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 574	$ 422	$ 370	$ 14	$ 1,549	$ 1,098	$ 881	$ 1,571	$ 1,380	$ 5,099	$ 6,654
Net income (loss) available to MetLife, Inc.’s common shareholders per common share:
Basic	$ 0.78	$ 0.56	$ 0.48	$ 0.02	$ 1.98	$ 1.38	$ 1.09	$ 1.91	$ 1.82	$ 6.35	$ 7.71
Diluted	$ 0.77	$ 0.56	$ 0.48	$ 0.02	$ 1.96	$ 1.37	$ 1.08	$ 1.89	$ 1.81	$ 6.30	$ 7.65