Earnings Per Common Share (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Weighted Average Shares:
Weighted average common stock outstanding - basic	723.2	775.4
Incremental common shares from assumed exercise or issuance of stock-based awards	5.2	5.8
Weighted average common stock outstanding - diluted	728.4	781.2
Net Income (Loss):
Net income (loss)	$ 875	$ 85
Less: Net income (loss) attributable to noncontrolling interests	8	5
Less: Preferred stock dividends	67	66
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 800	$ 14
Basic	$ 1.11	$ 0.02
Diluted	$ 1.10	$ 0.02