Earnings Per Common Share (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Weighted Average Shares:
Weighted average common stock outstanding - basic	710.5		765.9		716.8	770.6
Incremental common shares from assumed exercise or issuance of stock-based awards	4.2		3.7		4.7	4.8
Weighted average common stock outstanding - diluted	714.7		769.6		721.5	775.4
Net Income (Loss):
Net income (loss)	$ 953	$ 875	$ 408	$ 85	$ 1,828	$ 493
Less: Net income (loss) attributable to noncontrolling interests	7		6		15	11
Less: Preferred stock dividends	34	$ 67	32	$ 66	101	98
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 912		$ 370		$ 1,712	$ 384
Basic	$ 1.28		$ 0.48		$ 2.39	$ 0.50
Diluted	$ 1.28		$ 0.48		$ 2.37	$ 0.50