Condensed Financial Information (Parent Company) (Condensed Statements of Operations) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Net Investment Income									$ 18,868	$ 16,166	$ 17,363
Other revenues									1,842	1,880	1,341
Net investment gains (losses)									444	(298)	(308)
Net derivative gains (losses)									628	851	(590)
Total revenues	$ 17,143	$ 18,678	$ 17,497	$ 16,302	$ 15,662	$ 16,289	$ 21,185	$ 14,805	69,620	67,941	62,308
Expenses
Other expenses									13,689	13,714	13,621
Total expenses	17,180	15,887	15,200	14,558	13,191	15,210	20,084	13,149	62,825	61,634	58,772
Income (loss) from before provision for income tax									6,795	6,307	3,536
Provision for income tax expense (benefit)									886	1,179	(1,470)
Net income (loss)	593	2,184	1,741	1,381	2,067	912	891	1,253	5,899	5,123	4,010
Less: Preferred stock dividends	57	32	57	32	57	32	46	6	178	141	103
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 536	$ 2,152	$ 1,684	$ 1,349	$ 2,010	$ 880	$ 845	$ 1,247	5,721	4,982	3,907
Comprehensive income (loss)									17,208	(1,494)	7,391
Parent Company
Condensed Income Statements, Captions [Line Items]
Equity in earnings of subsidiaries									6,301	6,466	7,162
Net Investment Income									77	87	101
Other revenues									27	19	59
Net investment gains (losses)									(40)	(277)	(1,142)
Net derivative gains (losses)									(45)	(56)	(186)
Total revenues									6,320	6,239	5,994
Expenses
Interest expense									850	1,009	1,108
Other expenses									153	158	657
Total expenses									1,003	1,167	2,059
Income (loss) from before provision for income tax									5,317	5,072	3,935
Provision for income tax expense (benefit)									(582)	(51)	(75)
Net income (loss)									5,899	5,123	4,010
Less: Preferred stock dividends									178	141	103
Net income (loss) available to MetLife, Inc.’s common shareholders									5,721	4,982	3,907
Comprehensive income (loss)									17,208	(1,494)	7,391
Brighthouse Financial, Inc
Condensed Income Statements, Captions [Line Items]
Other revenues									246	305
Net investment gains (losses)											(1,016)
Expenses
Other expenses											(18)
Brighthouse Financial, Inc | Parent Company
Expenses
Termination of financing arrangements									$ 0	$ 0	$ 294