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, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Weighted Average Shares:
Weighted average common stock outstanding - basic	670.8		710.5		676.5	716.8
Incremental common shares from assumed exercise or issuance of stock-based awards	4.2		4.2		4.5	4.7
Weighted average common stock outstanding - diluted	675.0		714.7		681.0	721.5
Net Income (Loss):
Net income (loss)	$ 735	$ 950	$ 953	$ 875	$ 1,685	$ 1,828
Less: Net income (loss) attributable to noncontrolling interests	6		7		11	15
Less: Preferred stock dividends	31	$ 66	34	$ 67	97	101
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 698		$ 912		$ 1,577	$ 1,712
Basic	$ 1.04		$ 1.28		$ 2.33	$ 2.39
Diluted	$ 1.03		$ 1.28		$ 2.32	$ 2.37