Summary of Net Operating Income (Loss) for Segments and Corporate and Other Activities (Detail) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		Dec. 31, 2021		Sep. 30, 2021		Jun. 30, 2021		Mar. 31, 2021		Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Net income available to Genworth Financial, Inc.'s common stockholders		$ 163	[1]	$ 314	[1]	$ 240	[1]	$ 187	[1]	$ 267		$ 418		$ (441)		$ (66)		$ 904	$ 178	$ 343
Add: net income (loss) from continuing operations attributable to noncontrolling interests		29	[1]	4	[1]	0	[1]	0	[1]	0		0		0		0		33	0	0
Add: net income from discontinued operations attributable to noncontrolling interests		0		0		0		8		(1)		18		23		(6)		8	34	187
Net income		192	[2],[3],[4]	318	[2],[3],[4]	240	[2],[3],[4]	195	[2],[3],[4]	266	[5],[6],[7],[8]	436	[5],[6],[7],[8]	(418)	[5],[6],[7],[8]	(72)	[5],[6],[7],[8]	945	212	530
Income (loss) from discontinued operations, net of taxes		(1)		12		(5)		21		(35)	[7]	34	[7]	(473)	[7]	(12)	[7]	27	(486)	148
Income from continuing operations		193	[2],[3],[4]	306	[2],[3],[4]	245	[2],[3],[4]	174	[2],[3],[4]	301	[5],[6],[8]	402	[5],[6],[8]	55	[5],[6],[8]	(60)	[5],[6],[8]	918	698	382
Less: net income from continuing operations attributable to noncontrolling interests		29	[1]	4	[1]	0	[1]	0	[1]	0		0		0		0		33	0	0
Income from continuing operations available to Genworth Financial, Inc.'s common stockholders		164		$ 302		$ 245		$ 174		$ 301		$ 402		$ 55		$ (60)		885	698	382
Net investment (gains) losses, net	[9]																	(324)	(503)	(38)
(Gains) losses on early extinguishment of debt																		45	9	0
Initial loss from life block transaction		$ 92																92	0	0
Expenses related to restructuring																		34	3	4
Taxes on adjustments																		33	103	7
Adjusted operating income (loss) available to Genworth Financial, Inc.'s common stockholders																		765	310	355
Segment, Continuing Operations
Segment Reporting Information [Line Items]
Net income available to Genworth Financial, Inc.'s common stockholders																		904	178	343
Add: net income (loss) from continuing operations attributable to noncontrolling interests																		33	0	0
Net income																		945	212	530
Income from continuing operations																		918	698	382
Less: net income from continuing operations attributable to noncontrolling interests																		33	0	0
Income from continuing operations available to Genworth Financial, Inc.'s common stockholders																		885	698	382
Segment, Continuing Operations | Long-term Care Insurance
Segment Reporting Information [Line Items]
Adjusted operating income (loss) available to Genworth Financial, Inc.'s common stockholders																		445	237	57
Segment, Continuing Operations | Life Insurance
Segment Reporting Information [Line Items]
Adjusted operating income (loss) available to Genworth Financial, Inc.'s common stockholders																		(269)	(247)	(181)
Segment, Continuing Operations | Fixed Annuities
Segment Reporting Information [Line Items]
Adjusted operating income (loss) available to Genworth Financial, Inc.'s common stockholders																		91	78	69
Segment, Continuing Operations | U.S. Life Insurance
Segment Reporting Information [Line Items]
Net income available to Genworth Financial, Inc.'s common stockholders																		441	478	13
Add: net income (loss) from continuing operations attributable to noncontrolling interests																		0	0	0
Net income																		441	478	13
Income from continuing operations																		441	478	13
Less: net income from continuing operations attributable to noncontrolling interests																		0	0	0
Income from continuing operations available to Genworth Financial, Inc.'s common stockholders																		441	478	13
Adjusted operating income (loss) available to Genworth Financial, Inc.'s common stockholders																		267	68	(55)
Segment, Continuing Operations | Runoff
Segment Reporting Information [Line Items]
Net income available to Genworth Financial, Inc.'s common stockholders																		56	25	39
Add: net income (loss) from continuing operations attributable to noncontrolling interests																		0	0	0
Net income																		56	25	39
Income from continuing operations																		56	25	39
Less: net income from continuing operations attributable to noncontrolling interests																		0	0	0
Income from continuing operations available to Genworth Financial, Inc.'s common stockholders																		56	25	39
Adjusted operating income (loss) available to Genworth Financial, Inc.'s common stockholders																		54	43	56
Segment, Continuing Operations | Corporate and Other
Segment Reporting Information [Line Items]
Net income available to Genworth Financial, Inc.'s common stockholders																		(109)	(703)	(278)
Add: net income (loss) from continuing operations attributable to noncontrolling interests																		0	0	0
Net income																		(101)	(669)	(91)
Income from continuing operations																		(128)	(183)	(239)
Less: net income from continuing operations attributable to noncontrolling interests																		0	0	0
Income from continuing operations available to Genworth Financial, Inc.'s common stockholders																		(128)	(183)	(239)
Adjusted operating income (loss) available to Genworth Financial, Inc.'s common stockholders																		(76)	(182)	(214)
Segment, Continuing Operations | Enact [Member]
Segment Reporting Information [Line Items]
Net income available to Genworth Financial, Inc.'s common stockholders																		516	378	569
Add: net income (loss) from continuing operations attributable to noncontrolling interests																		33	0	0
Net income																		549	378	569
Income from continuing operations																		549	378	569
Less: net income from continuing operations attributable to noncontrolling interests																		33	0	0
Income from continuing operations available to Genworth Financial, Inc.'s common stockholders																		516	378	569
Adjusted operating income (loss) available to Genworth Financial, Inc.'s common stockholders																		$ 520	$ 381	$ 568

[1] On September 20, 2021, we completed the minority IPO of Enact Holdings, which reduced our ownership percentage to 81.6%, and lowered our available net income by $29 million in the fourth quarter of 2021.

[2] In the fourth quarter of 2021, our life insurance business initially ceded $268 million of certain term life insurance reserves under a new reinsurance treaty as part of a life block transaction. Our life insurance business also completed its annual review of assumptions in the fourth quarter of 2021. This review resulted in higher total benefits and expenses of $87 million from an unfavorable unlocking in our term universal and universal life insurance products largely attributable to higher pre-COVID-19 mortality. In our term universal life insurance products, we also recorded a DAC impairment of $41 million in the fourth quarter of 2021 principally due to lower future estimated gross profits.

[3] In the fourth quarter of 2021, our life insurance business initially ceded $360 million of premiums associated with certain term life insurance policies under a new reinsurance treaty as part of a life block transaction.

[4] In the fourth quarter of 2021, our life insurance business recorded a net loss of $131 million predominantly driven by an initial loss of $73 million as a result of ceding certain term life insurance policies as part of a life block transaction, an unfavorable unlocking of $70 million associated with its annual review of assumptions and a DAC impairment of $32 million as a result of recoverability testing.

[5] Given our assumption that COVID-19 has temporarily decreased the number of new claims submitted, our long-term care insurance business strengthened IBNR reserves in the fourth quarter of 2020 by $47 million. Additionally, our long-term care insurance business recorded a $91 million increase to claim reserves reflecting our assumption that COVID-19 accelerated mortality experience on the most vulnerable claimants, leaving the remaining claim population less likely to terminate compared to the pre-pandemic average population. Our Enact segment recorded an unfavorable reserve adjustment of $37 million primarily due to slowing cure emergence patterns impacting the frequency of claim. Our life insurance business completed its annual review of assumptions in the fourth quarter of 2020. This review resulted in lower total benefits and expenses of $82 million from a net favorable unlocking in our term universal and universal life insurance products largely attributable to a model refinement in our term universal life insurance product related to persistency and grace period timing and lower projected cost of insurance assessments on our universal life insurance products. In addition, we recorded a DAC impairment of $63 million in our universal life insurance products due principally to lower future estimated gross profits.

[6] In the fourth quarter of 2020, our long-term care insurance business strengthened its reserves by $109 million after-tax. Our Enact segment strengthened loss reserves by $29 million after-tax. Our life insurance business recorded a $60 million net favorable unlocking, net of taxes, related to its annual review of assumptions. This favorable unlocking in our life insurance business was partially offset by a DAC impairment of $50 million, net of taxes, as a result of recoverability testing. For all of the aforementioned transactions, see above under superscript (2) for additional details.

[7] In the fourth quarter of 2020, we recorded a loss from discontinued operations, net of taxes, of $35 million principally attributed to expenses associated with the promissory note owed to AXA and from a $5 million net loss in Genworth Australia. The expenses associated with the promissory note mostly consisted of foreign currency remeasurement losses of $26 million, unfavorable tax charges of $17 million and other expenses of $8 million. These expenses were partially offset by derivative hedge gains of $21 million associated with foreign currency forward contracts entered into to mitigate our exposure to the installment payments to be made in British Pounds in 2022. See note 23 for additional details on discontinued operations.

[8] In the fourth quarter of 2020, we recorded lower net investment gains as compared to the third quarter of 2020. The higher net investment gains recorded in the third quarter of 2020 related to the sale of available-for-sale fixed maturity securities of $330 million driven primarily from the sale of U.S. government securities due to portfolio rebalancing and asset exposure management as a result of the prolonged low interest rate environment. This decrease to total revenues was partially offset by higher net investment income recorded in the fourth quarter of 2020 largely driven by bond calls and mortgage loan repayments of $40 million and limited partnerships of $38 million.

[9] For the years ended December 31, 2021, 2020 and 2019, net investment (gains) losses were adjusted for DAC and other intangible amortization and certain benefit reserves of $(1) million, $(11) million and $(11) million, respectively.