Condensed Financial Information (Parent Company) (Condensed Statements of Cash Flows) (Details) - 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
Cash flows from operating activities
Net income (loss)	$ 607	$ 489	$ 402	$ 80	$ 1,578	$ 1,162	$ 910	$ 1,634	$ 1,578	$ 5,284	$ 6,855
(Gains) losses on investments and from sales of businesses, net									2,800	1,260	(1,543)
Other, net									197	245	113
Net cash provided by (used in) operating activities									13,721	13,044	12,347
Cash flows from investing activities
Sales, maturities and repayments of fixed maturity securities available-for-sale									58,816	88,937	88,839
Purchases of fixed maturity securities available-for-sale									(63,460)	(82,956)	(97,368)
Sales, maturities and repayments of short-term investments									13,117	14,094	20,871
Purchases of short-term investments									(14,000)	(11,741)	(24,148)
Cash received in connection with freestanding derivatives									3,145	4,524	3,453
Cash paid in connection with freestanding derivatives									(5,662)	(7,793)	(7,990)
Other, net									(143)	(63)	(46)
Net cash provided by (used in) investing activities									(10,246)	(2,620)	(11,187)
Cash flows from financing activities
Net change in payables for collateral under securities loaned and other transactions									(3,283)	(10,730)	1,883
Long-term debt issued									1,989	1,013	29
Long-term debt repaid									(1,035)	(85)	(582)
Treasury stock acquired in connection with share repurchases									(3,103)	(3,326)	(4,303)
Redemption of preferred stock									0	0	(494)
Preferred stock redemption premium									0	0	(6)
Dividends on preferred stock									(198)	(185)	(195)
Dividends on common stock									(1,566)	(1,598)	(1,647)
Other, net									(139)	(236)	22
Net cash provided by (used in) financing activities									(2,940)	(9,948)	(1,126)
Cash and cash equivalents, from continuing operations, beginning of year				20,195					20,195
Cash and cash equivalents, from continuing operations, end of year	20,639				20,195				20,639	20,195
Supplemental disclosures of cash flow information
Net cash paid (received) for Income tax									1,833	1,056	1,102
Parent Company
Cash flows from operating activities
Net income (loss)									1,578	5,284	6,855
Earnings of subsidiaries									(2,199)	(5,619)	(6,296)
Dividends from subsidiaries									4,780	5,168	4,830
(Gains) losses on investments and from sales of businesses, net									(134)	(332)	(1,655)
Other, net									158	(73)	23
Net cash provided by (used in) operating activities									4,183	4,428	3,757
Cash flows from investing activities
Sales, maturities and repayments of fixed maturity securities available-for-sale									3,093	1,609	5,078
Purchases of fixed maturity securities available-for-sale									(973)	(2,757)	(4,371)
Sales, maturities and repayments of short-term investments									1,330	0	0
Purchases of short-term investments									(1,375)	0	0
Net change in short-term investments									0	0	156
Cash received in connection with freestanding derivatives									161	296	111
Cash paid in connection with freestanding derivatives									(155)	(103)	(27)
Sales of businesses									0	0	3,902
Expense paid on behalf of subsidiaries									(4)	(10)	(15)
Receipts on loans to subsidiaries									250	150	195
Issuances of loans to subsidiaries									(460)	(210)	(230)
Returns of capital from subsidiaries									6	8	13
Capital contributions to subsidiaries									(528)	(5)	(88)
Other, net									(3)	15	9
Net cash provided by (used in) investing activities									1,342	(1,007)	4,733
Cash flows from financing activities
Net change in payables for collateral under securities loaned and other transactions									111	1	88
Long-term debt issued									1,986	1,000	496
Long-term debt repaid									(1,000)	0	(996)
Treasury stock acquired in connection with share repurchases									(3,103)	(3,326)	(4,303)
Redemption of preferred stock									0	0	(494)
Preferred stock redemption premium									0	0	(6)
Dividends on preferred stock									(198)	(185)	(195)
Dividends on common stock									(1,566)	(1,598)	(1,647)
Other, net									(24)	16	87
Net cash provided by (used in) financing activities									(3,794)	(4,092)	(6,970)
Change in cash and cash equivalents									1,731	(671)	1,520
Cash and cash equivalents, from continuing operations, beginning of year				$ 1,290				$ 1,961	1,290	1,961	441
Cash and cash equivalents, from continuing operations, end of year	$ 3,021				$ 1,290				3,021	1,290	1,961
Supplemental disclosures of cash flow information
Net cash paid for Interest									852	800	853
Net cash paid (received) for Income tax									(165)	(129)	18
Non-cash transactions:
Dividends from subsidiary									0	0	14
Returns of capital from subsidiaries									2	12	7
Capital contributions to subsidiaries									1	11	15
Amounts paid to (received from) subsidiaries, net | Parent Company
Supplemental disclosures of cash flow information
Net cash paid (received) for Income tax									(671)	(214)	(110)
Income tax paid (received) by MetLife, Inc., net | Parent Company
Supplemental disclosures of cash flow information
Net cash paid (received) for Income tax									$ 506	$ 85	$ 128