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, 2022	Sep. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Weighted Average Shares:
Weighted average common stock outstanding - basic	795.8	854.9			809.7	871.1
Incremental common shares from assumed exercise or issuance of stock-based awards	4.9	6.3			5.5	6.4
Weighted average common stock outstanding - diluted	800.7	861.2			815.2	877.5
Net Income (Loss):
Net income (loss)	$ 400	$ 1,589	$ 812	$ 3,775	$ 1,212	$ 5,364
Less: Net income (loss) attributable to noncontrolling interests	5	5			16	15
Less: Preferred stock dividends	64	63	$ 92	103	156	166
Preferred stock redemption premium	0	0		$ 6	0	6
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 331	$ 1,521			$ 1,040	$ 5,177
Basic	$ 0.42	$ 1.78			$ 1.28	$ 5.94
Diluted	$ 0.41	$ 1.77			$ 1.28	$ 5.90