Intangibles - Narrative (Detail) - USD ($)	1 Months Ended	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2020	Jun. 01, 2020
Finite-Lived Intangible Assets [Line Items]
Unearned revenue liability		$ (1,000,000)
Deferrals		(17,000,000)
Amortization expense		3,000,000
Interest		0
Unlocking		0
Unrealized investment gain (losses)		$ 13,000,000
VOBA
Finite-Lived Intangible Assets [Line Items]
Adjustment for net unrealized investment gains	$ (228,000,000)
VOBA | Minimum
Finite-Lived Intangible Assets [Line Items]
Interest accrual rate utilized to calculate accretion of interest	0.00%
VOBA | Maximum
Finite-Lived Intangible Assets [Line Items]
Interest accrual rate utilized to calculate accretion of interest	4.71%
DAC
Finite-Lived Intangible Assets [Line Items]
Cumulative adjustments for net unrealized investment gains			$ 15,000,000
Deferred sales inducement, unrealized investment gain	$ 4,000,000