Earnings Per Common Share (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Weighted Average Shares:
Weighted average common stock outstanding - basic	823.8	885.4
Incremental common shares from assumed exercise or issuance of stock-based awards	6.7	6.7
Weighted average common stock outstanding - diluted	830.5	892.1
Net Income (Loss):
Net income (loss)	$ 674	$ 363
Less: Net income (loss) attributable to noncontrolling interests	5	5
Less: Preferred stock dividends	63	68
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 606	$ 290
Basic	$ 0.74	$ 0.33
Diluted	$ 0.73	$ 0.33