Investments (Changes in Net Unrealized Investment Gains Losses) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2022 USD ($)
Changes In Net Unrealized Investment Gains Losses Included In Accumulated Other Comprehensive Loss [Abstract]
Balance, beginning of period	$ 17,671
Unrealized investment gains (losses) during the period	(44,572)
Unrealized investment gains (losses) relating to:
Policyholder liabilities	4,128
DAC, VOBA and DSI	5,260
Deferred income tax benefit (expense)	8,054
Net unrealized investment gains (losses)	(9,459)
Net unrealized investment gains (losses) attributable to noncontrolling interests	2
Balance, end of period	(9,457)
Change in net unrealized investment gains (losses)	(27,130)
Change in net unrealized investment gains (losses) attributable to noncontrolling interests	2
Change in net unrealized investment gains (losses) attributable to MetLife, Inc.	$ (27,128)