Investments (Net Unrealized Investment Gains Losses) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Components of net unrealized investment gains (losses) included in accumulated other comprehensive income
Fixed maturity securities AFS	$ 6,413	$ 29,461
Derivatives	1,861	2,061
Other	337	389
Subtotal	8,611	31,911
Policyholder liabilities	(427)	(4,978)
DAC, VOBA and DSI	(743)	(3,208)
Subtotal	(1,170)	(8,186)
Deferred income tax benefit (expense)	(2,237)	(6,031)
Net unrealized investment gains (losses)	5,204	17,694
Net unrealized investment gains (losses) attributable to noncontrolling interests	(22)	(23)
Net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 5,182	$ 17,671