Earnings Per Common Share (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Weighted Average Shares:
Weighted average common stock outstanding - basic	699.3	751.4			710.9	764.1
Incremental common shares from assumed exercise or issuance of stock-based awards	4.4	4.1			4.6	4.6
Weighted average common stock outstanding - diluted	703.7	755.5			715.5	768.7
Net Income (Loss):
Net income (loss)	$ 1,341	$ 495	$ 1,828	$ 493	$ 3,169	$ 988
Less: Net income (loss) attributable to noncontrolling interests	(1)	6			14	17
Less: Preferred stock dividends	67	67	$ 101	$ 98	168	165
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 1,275	$ 422			$ 2,987	$ 806
Basic	$ 1.82	$ 0.56			$ 4.20	$ 1.05
Diluted	$ 1.81	$ 0.56			$ 4.17	$ 1.05