Condensed Financial Information (Parent Company) (Condensed Statements of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net income (loss)	$ 6,554	$ 5,407	$ 5,899
(Gains) losses on investments and from sales of businesses, net	(1,529)	110	(444)
Other, net	138	351	285
Net cash provided by (used in) operating activities	12,596	11,639	13,786
Cash flows from investing activities
Sales and maturities of fixed maturity securities available-for-sale	88,839	77,979	77,820
Purchases of fixed maturity securities available-for-sale	(97,368)	(89,633)	(87,455)
Cash received in connection with freestanding derivatives	3,453	4,847	2,914
Cash paid in connection with freestanding derivatives	(7,990)	(4,247)	(3,749)
Sales of businesses	3,902	0	0
Issuances of loans to subsidiaries	230	0	0
Net change in short-term investments	(3,277)	(341)	152
Other, net	(46)	139	(131)
Net cash provided by (used in) investing activities	(11,187)	(18,569)	(17,586)
Cash flows from financing activities
Net change in payables for collateral under securities loaned and other transactions	1,883	3,538	2,019
Long-term debt issued	29	1,124	1,382
Long-term debt repaid	(582)	(99)	(906)
Treasury stock acquired in connection with share repurchases	(4,303)	(1,151)	(2,285)
Preferred stock issued, net of issuance costs	0	1,961	0
Redemption of preferred stock	(494)	(989)	0
Preferred stock redemption premium	(6)	(14)	0
Dividends on preferred stock	(195)	(202)	(178)
Dividends on common stock	(1,647)	(1,657)	(1,643)
Other, net	22	191	(77)
Net cash provided by (used in) financing activities	(1,375)	10,729	4,568
Cash and cash equivalents, from continuing operations, beginning of year	19,795
Cash and cash equivalents, from continuing operations, end of year	20,047	19,795
Supplemental disclosures of cash flow information
Net cash paid (received) for Income tax	1,102	787	1,099
Parent Company
Cash flows from operating activities
Net income (loss)	6,554	5,407	5,899
Earnings of subsidiaries	(5,995)	(6,263)	(6,301)
Dividends from subsidiaries	4,830	3,970	4,790
(Gains) losses on investments and from sales of businesses, net	(1,655)	154	40
Other, net	23	211	(251)
Net cash provided by (used in) operating activities	3,757	3,479	4,177
Cash flows from investing activities
Sales and maturities of fixed maturity securities available-for-sale	5,078	3,693	3,153
Purchases of fixed maturity securities available-for-sale	(4,371)	(3,858)	(3,380)
Cash received in connection with freestanding derivatives	111	71	101
Cash paid in connection with freestanding derivatives	(27)	(100)	(392)
Purchases of businesses	0	(1,875)	0
Expense paid on behalf of subsidiaries	(15)	(15)	(13)
Receipts on loans to subsidiaries	195	100	0
Returns of capital from subsidiaries	13	16	10
Capital contributions to subsidiaries	(88)	(422)	(75)
Net change in short-term investments	156	4	14
Other, net	9	(2)	28
Net cash provided by (used in) investing activities	4,733	(2,388)	(554)
Cash flows from financing activities
Net change in payables for collateral under securities loaned and other transactions	88	49	7
Long-term debt issued	496	1,246	1,382
Long-term debt repaid	(996)	(251)	(877)
Treasury stock acquired in connection with share repurchases	(4,303)	(1,151)	(2,285)
Preferred stock issued, net of issuance costs	0	1,961	0
Redemption of preferred stock	(494)	(989)	0
Preferred stock redemption premium	(6)	(14)	0
Dividends on preferred stock	(195)	(202)	(178)
Dividends on common stock	(1,647)	(1,657)	(1,643)
Other, net	87	(19)	(28)
Net cash provided by (used in) financing activities	(6,970)	(1,027)	(3,622)
Change in cash and cash equivalents	1,520	64	1
Cash and cash equivalents, from continuing operations, beginning of year	441	377	376
Cash and cash equivalents, from continuing operations, end of year	1,961	441	377
Supplemental disclosures of cash flow information
Net cash paid for Interest	853	815	864
Net cash paid (received) for Income tax	18	(296)	(155)
Non-cash transactions:
Dividends from subsidiary	14	341	0
Returns of capital from subsidiaries	7	13	29
Capital contributions to subsidiaries	15	1	30
Amounts paid to (received from) subsidiaries, net | Parent Company
Supplemental disclosures of cash flow information
Net cash paid (received) for Income tax	(110)	(392)	(152)
Income tax paid (received) by MetLife, Inc., net | Parent Company
Supplemental disclosures of cash flow information
Net cash paid (received) for Income tax	$ 128	$ 96	$ (3)