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	$ (4,024)	$ 708			$ (469)	$ 172
Provision for income tax expense (benefit)	(858)	99			(145)	(46)
Post-tax adjusted earnings	(3,166)	609	$ 2,842	$ (391)	(324)	218
Less: Net income (loss) attributable to noncontrolling interests	0	0			1	1
Net investment gains (losses)	6	14			(46)	60
Net derivative gains (losses)	(1,870)	984			2,227	(218)
Other adjustments to net income (loss)	73	68			224	199
Net income (loss) attributable to Brighthouse Life Insurance Company	(3,166)	609			(325)	217
Annuities
Segment Reporting Information [Line Items]
Interest revenue	467	458			1,327	1,344
Interest expense	0	0			0	0
Life
Segment Reporting Information [Line Items]
Interest revenue	116	101			273	284
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	17	18			48	40
Interest expense	17	17			51	43
Operating Segments
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	(1,112)	(278)			(886)	303
Provision for income tax expense (benefit)	(246)	(109)			(232)	(19)
Post-tax adjusted earnings	(866)	(169)			(654)	322
Less: Net income (loss) attributable to noncontrolling interests	0	0			1	1
Adjusted earnings	(866)	(169)			(655)	321
Operating Segments | Annuities
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	466	247			1,042	915
Provision for income tax expense (benefit)	90	50			194	172
Post-tax adjusted earnings	376	197			848	743
Less: Net income (loss) attributable to noncontrolling interests	0	0			0	0
Adjusted earnings	376	197			848	743
Operating Segments | Life
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	(75)	88			(8)	185
Provision for income tax expense (benefit)	(17)	18			(3)	38
Post-tax adjusted earnings	(58)	70			(5)	147
Less: Net income (loss) attributable to noncontrolling interests	0	0			0	0
Adjusted earnings	(58)	70			(5)	147
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
Adjusted earnings	(1,139)	(426)			(1,324)	(460)
Operating Segments | Corporate & Other
Segment Reporting Information [Line Items]
Pre-tax adjusted earnings	(60)	(70)			(241)	(210)
Provision for income tax expense (benefit)	(15)	(60)			(68)	(102)
Post-tax adjusted earnings	(45)	(10)			(173)	(108)
Less: Net income (loss) attributable to noncontrolling interests	0	0			1	1
Adjusted earnings	(45)	(10)			(174)	(109)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Provision for income tax expense (benefit)	612	(208)			(87)	27
Net investment gains (losses)	6	14			(46)	60
Net derivative gains (losses)	(1,870)	984			2,227	(218)
Other adjustments to net income (loss)	$ (1,048)	$ (12)			$ (1,764)	$ 27