Segment Information (Operating Results) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	$ (3,843)	$ 804			$ (113)	$ 320
Provision for income tax expense (benefit)	(850)	119			(88)	(14)
Post-tax adjusted earnings	(2,993)	685	$ 2,968	$ (351)	(25)	334
Less: Net income (loss) attributable to noncontrolling interests	2	2			4	4
Less: Preferred stock dividends	17	7			31	14
Net investment gains (losses)	5	27			(48)	79
Net derivative gains (losses)	(1,857)	1,057			2,392	(97)
Other adjustments to net income (loss)	99	94			294	282
Net income (loss) available to Brighthouse Financial, Inc.’s common shareholders	(3,012)	676			(60)	316
Annuities
Segment Reporting Information [Line Items]
Interest revenue	469	461			1,334	1,352
Interest expense	0	0			0	0
Life
Segment Reporting Information [Line Items]
Interest revenue	131	117			316	330
Interest expense	0	0			0	0
Run-off
Segment Reporting Information [Line Items]
Interest revenue	383	327			873	942
Interest expense	0	0			0	0
Corporate & Other
Segment Reporting Information [Line Items]
Interest revenue	18	23			54	57
Interest expense	47	49			139	144
Operating Segments
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	(902)	(264)			(628)	322
Provision for income tax expense (benefit)	(232)	(104)			(196)	(13)
Post-tax adjusted earnings	(670)	(160)			(432)	335
Less: Net income (loss) attributable to noncontrolling interests	2	2			4	4
Less: Preferred stock dividends	17	7			31	14
Adjusted earnings	(689)	(169)			(467)	317
Operating Segments | Annuities
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	479	255			1,073	939
Provision for income tax expense (benefit)	92	52			199	176
Post-tax adjusted earnings	387	203			874	763
Less: Net income (loss) attributable to noncontrolling interests	0	0			0	0
Less: Preferred stock dividends	0	0			0	0
Adjusted earnings	387	203			874	763
Operating Segments | Life
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	94	91			167	194
Provision for income tax expense (benefit)	18	18			32	38
Post-tax adjusted earnings	76	73			135	156
Less: Net income (loss) attributable to noncontrolling interests	0	0			0	0
Less: Preferred stock dividends	0	0			0	0
Adjusted earnings	76	73			135	156
Operating Segments | Run-off
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	(1,443)	(543)			(1,679)	(587)
Provision for income tax expense (benefit)	(304)	(117)			(355)	(127)
Post-tax adjusted earnings	(1,139)	(426)			(1,324)	(460)
Less: Net income (loss) attributable to noncontrolling interests	0	0			0	0
Less: Preferred stock dividends	0	0			0	0
Adjusted earnings	(1,139)	(426)			(1,324)	(460)
Operating Segments | Corporate & Other
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	(32)	(67)			(189)	(224)
Provision for income tax expense (benefit)	(38)	(57)			(72)	(100)
Post-tax adjusted earnings	6	(10)			(117)	(124)
Less: Net income (loss) attributable to noncontrolling interests	2	2			4	4
Less: Preferred stock dividends	17	7			31	14
Adjusted earnings	(13)	(19)			(152)	(142)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Provision for income tax expense (benefit)	618	(223)			(108)	1
Net investment gains (losses)	5	27			(48)	79
Net derivative gains (losses)	(1,857)	1,057			2,392	(97)
Other adjustments to net income (loss)	$ (1,089)	$ (16)			$ (1,829)	$ 16