Segment Information (Operating Results) (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
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings									$ (1,052)	$ 989	$ (615)
Provision for income tax expense (benefit)									(317)	119	(237)
Post-tax adjusted earnings	$ (1,069)	$ 685	$ 384	$ (735)	$ 1,442	$ (269)	$ (238)	$ (65)	(735)	870	(378)
Less: Net income (loss) attributable to noncontrolling interests	1	2	0	2	0	2	1	2	5	5	0
Less: Preferred stock dividends	7	7	7	0	0	0	0	0	21	0	0
Net investment gains (losses)									112	(207)	(28)
Net derivative gains (losses)									(1,988)	702	(1,620)
Other adjustments to net income (loss)									389	397	651
Net income (loss) available to Brighthouse Financial, Inc.'s common shareholders	$ (1,077)	$ 676	$ 377	$ (737)	$ 1,442	$ (271)	$ (239)	$ (67)	(761)	865	(378)
Annuities
Segment Reporting Information [Line Items]
Interest revenue									1,809	1,536	1,277
Interest expense									0	0	0
Life
Segment Reporting Information [Line Items]
Interest revenue									436	449	342
Interest expense									0	0	0
Run-off
Segment Reporting Information [Line Items]
Interest revenue									1,265	1,310	1,399
Interest expense									0	0	23
Corporate & Other
Segment Reporting Information [Line Items]
Interest revenue									75	57	192
Interest expense									191	158	132
Operating Segments
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings									670	1,030	1,597
Provision for income tax expense (benefit)									45	133	677
Post-tax adjusted earnings									625	897	920
Less: Net income (loss) attributable to noncontrolling interests									5	5	0
Less: Preferred stock dividends									21	0	0
Adjusted earnings									599	892	920
Operating Segments | Annuities
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings									1,263	1,233	1,386
Provision for income tax expense (benefit)									235	210	369
Post-tax adjusted earnings									1,028	1,023	1,017
Less: Net income (loss) attributable to noncontrolling interests									0	0	0
Less: Preferred stock dividends									0	0	0
Adjusted earnings									1,028	1,023	1,017
Operating Segments | Life
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings									288	285	7
Provision for income tax expense (benefit)									57	57	(9)
Post-tax adjusted earnings									231	228	16
Less: Net income (loss) attributable to noncontrolling interests									0	0	0
Less: Preferred stock dividends									0	0	0
Adjusted earnings									231	228	16
Operating Segments | Run-off
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings									(580)	(57)	147
Provision for income tax expense (benefit)									(126)	(14)	43
Post-tax adjusted earnings									(454)	(43)	104
Less: Net income (loss) attributable to noncontrolling interests									0	0	0
Less: Preferred stock dividends									0	0	0
Adjusted earnings									(454)	(43)	104
Operating Segments | Corporate & Other
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings									(301)	(431)	57
Provision for income tax expense (benefit)									(121)	(120)	274
Post-tax adjusted earnings									(180)	(311)	(217)
Less: Net income (loss) attributable to noncontrolling interests									5	5	0
Less: Preferred stock dividends									21	0	0
Adjusted earnings									(206)	(316)	(217)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Provision for income tax expense (benefit)									362	14	914
Net investment gains (losses)									112	(207)	(28)
Net derivative gains (losses)									(1,988)	702	(1,620)
Other adjustments to net income (loss)									$ 154	$ (536)	$ (564)