Borrowings and Other Financings - Additional Information (Detail) AUD in Millions		1 Months Ended			3 Months Ended		12 Months Ended
		Jun. 30, 2016 AUD	Jan. 31, 2016 USD ($)	Jul. 31, 2015 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2017 AUD	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 CAD	Sep. 29, 2017 CAD	Apr. 30, 2016 USD ($)	Jul. 31, 2015 AUD
Nonrecourse Funding Obligations [Line Items]
Broker, advisor and investment banking fees								$ 0	$ 18,000,000	$ 0
Pre-tax gain (loss) on repurchase of senior notes	[1]							0	48,000,000	(2,000,000)
Non-recourse funding obligationsTotal								310,000,000	310,000,000
Redemption of secured debt								0	1,620,000,000	61,000,000
Gains (losses) from life block transactions								0	(9,000,000)	$ (455,000,000)
Repurchase agreements, fair value of securities pledged									79,000,000
Repurchase agreements, fair value of repurchase obligation									75,000,000
Repayment of investment securities under repurchase agreements								75,000,000
Securities lending activity, obligation to return collateral								$ 268,000,000	534,000,000
Risks associated with repurchase agreements and securities lending programs							Our repurchase agreement and securities lending programs expose us to liquidity risk if we did not have enough cash or collateral readily available to return to the counterparty when required to do so under the agreements. We manage this risk by regularly monitoring our available sources of cash and collateral to ensure we can meet short-term liquidity demands under normal and stressed scenarios. We are also exposed to credit risk in the event of default of our counterparties or changes in collateral values. This risk is significantly reduced because our programs require over collateralization and collateral exposures are trued up on a daily basis. We manage this risk by using multiple counterparties and ensuring that changes in required collateral are monitored and adjusted daily. We also monitor the creditworthiness, including credit ratings, of our counterparties on a regular basis.	Our repurchase agreement and securities lending programs expose us to liquidity risk if we did not have enough cash or collateral readily available to return to the counterparty when required to do so under the agreements. We manage this risk by regularly monitoring our available sources of cash and collateral to ensure we can meet short-term liquidity demands under normal and stressed scenarios. We are also exposed to credit risk in the event of default of our counterparties or changes in collateral values. This risk is significantly reduced because our programs require over collateralization and collateral exposures are trued up on a daily basis. We manage this risk by using multiple counterparties and ensuring that changes in required collateral are monitored and adjusted daily. We also monitor the creditworthiness, including credit ratings, of our counterparties on a regular basis.
Life Block Transaction | Term Life Insurance
Nonrecourse Funding Obligations [Line Items]
Gains (losses) from life block transactions					$ (9,000,000)
United States
Nonrecourse Funding Obligations [Line Items]
Cash and government securities collateral, minimum amount of the fair value of the applicable securities loaned								102.00%			102.00%
Securities lending activity, fair value of securities loaned								$ 258,000,000	517,000,000
Securities lending activity, fair value of collateral held								268,000,000	534,000,000
Securities lending activity, obligation to return collateral								$ 268,000,000	534,000,000
Canada
Nonrecourse Funding Obligations [Line Items]
Cash and government securities collateral, minimum amount of the fair value of the applicable securities loaned								105.00%			105.00%
Securities lending activity, fair value of securities loaned								$ 382,000,000	$ 350,000,000
Non-Recourse Funding Obligations
Nonrecourse Funding Obligations [Line Items]
Non-recourse funding obligations weighted-average interest rate								3.54%	2.75%		3.54%
Non-Recourse Funding Obligations | Floating Rate Subordinated Notes Due 2033
Nonrecourse Funding Obligations [Line Items]
Debt instrument, maturity year							2033	2033		2033
Redemption of secured debt					975,000,000					$ 30,000,000
Non-Recourse Funding Obligations | Floating Rate Subordinated Notes Due in 2035
Nonrecourse Funding Obligations [Line Items]
Debt instrument, maturity year							2035	2035		2035
Redemption of secured debt					645,000,000					$ 31,000,000
Rivermont Life Insurance Company I Due 2050
Nonrecourse Funding Obligations [Line Items]
Debt instrument, maturity year							2050	2050
Non-recourse funding obligationsTotal								$ 310,000,000
Deferred borrowing charges									$ 5,000,000
Interest rate reset period, number of days							28 days	28 days
Genworth Canada
Nonrecourse Funding Obligations [Line Items]
Deferred borrowing charges								$ 1,000,000	$ 2,000,000
Genworth Canada | Syndicated senior unsecured revolving credit facility Due on September 29, 2022
Nonrecourse Funding Obligations [Line Items]
Facility, maximum borrowing capacity | CAD												CAD 200,000,000
Line of credit maturity date							Sep. 29, 2022	Sep. 29, 2022
Debt instrument, covenant description							As of December 31, 2017, there was no amount outstanding under Genworth Canada’s credit facility and all of the covenants were fully met.	As of December 31, 2017, there was no amount outstanding under Genworth Canada’s credit facility and all of the covenants were fully met.
Outstanding line of credit | CAD											CAD 0
Genworth Canada | Senior Unsecured Revolving Credit facility Canceled
Nonrecourse Funding Obligations [Line Items]
Facility, maximum borrowing capacity | CAD												CAD 100,000,000
Genworth Canada | 5.68% Senior Notes, Due 2020
Nonrecourse Funding Obligations [Line Items]
Interest rate								5.68%	5.68%		5.68%
Debt instrument, maturity year							2020	2020	2020
Genworth Canada | 4.24% Senior Notes, Due 2024
Nonrecourse Funding Obligations [Line Items]
Interest rate								4.24%			4.24%
Debt instrument, maturity year							2024	2024
Genworth Holdings
Nonrecourse Funding Obligations [Line Items]
Total Fees related to Consent Solicitation					61,000,000
Bond consent fees					43,000,000			$ 33,000,000	$ 39,000,000
Broker, advisor and investment banking fees					18,000,000				18,000,000
Pre-tax make-whole expense on redemption of senior notes									20,000,000
Aggregate principal amount of notes repurchased					28,000,000	$ 50,000,000			28,000,000	50,000,000
Pre-tax gain (loss) on repurchase of senior notes					$ 4,000,000	$ (1,000,000)			4,000,000	$ (1,000,000)
Deferred borrowing charges								$ 16,000,000	18,000,000
Genworth Holdings | Revolving Credit Facility Maturing September 2016
Nonrecourse Funding Obligations [Line Items]
Facility, maximum borrowing capacity													$ 300,000,000
Line of credit maturity date							Sep. 26, 2016	Sep. 26, 2016
Outstanding line of credit													$ 0
Genworth Holdings | Fixed Rate Senior Notes
Nonrecourse Funding Obligations [Line Items]
Debt instrument, redemption description							We have the option to redeem all or a portion of each series of senior notes at any time with notice to the noteholders at a price equal to the greater of 100% of principal or the sum of the present value of the remaining scheduled payments of principal and interest discounted at the then-current treasury rate plus an applicable spread.	We have the option to redeem all or a portion of each series of senior notes at any time with notice to the noteholders at a price equal to the greater of 100% of principal or the sum of the present value of the remaining scheduled payments of principal and interest discounted at the then-current treasury rate plus an applicable spread.
Genworth Holdings | Fixed Rate Senior Notes | Minimum
Nonrecourse Funding Obligations [Line Items]
Interest rate								4.80%			4.80%
Senior notes redemption option							100.00%	100.00%
Genworth Holdings | Fixed Rate Senior Notes | Maximum
Nonrecourse Funding Obligations [Line Items]
Interest rate								7.70%			7.70%
Genworth Holdings | 8.625% Senior Notes, Due 2016
Nonrecourse Funding Obligations [Line Items]
Interest rate			8.625%
Redemption of Long-term borrowings			$ 298,000,000
Pre-tax make-whole expense on redemption of senior notes			$ 20,000,000
Genworth Holdings | Junior Notes due Two Thousand and Sixty Six
Nonrecourse Funding Obligations [Line Items]
Interest rate								6.15%			6.15%
Issued notes, aggregate principal amount								$ 598,000,000
Debt instrument, maturity month and year							2066-11	2066-11
Quarterly interest rate after November 15, 2016							Three-month London Interbank Offered Rate (“LIBOR”) plus 2.0025%	Three-month London Interbank Offered Rate (“LIBOR”) plus 2.0025%
Scheduled redemption date							Nov. 15, 2036	Nov. 15, 2036
Right to defer the payment of interest on the 2066 Notes during period, years							10 years	10 years
Genworth Financial Mortgage Insurance Pty Limited
Nonrecourse Funding Obligations [Line Items]
Debt instrument, maturity year							2025	2025
Subordinated floating rate notes, margin							3.50%	3.50%
Deferred borrowing charges								$ 2,000,000	$ 3,000,000
Genworth Financial Mortgage Insurance Pty Limited | Floating Rate Junior Notes, Due 2021
Nonrecourse Funding Obligations [Line Items]
Redemption of Long-term borrowings | AUD		AUD 50
Subordinated floating rate notes, margin		4.75%
Genworth Financial Mortgage Insurance Pty Limited | Floating Rate Junior Notes, Due 2025
Nonrecourse Funding Obligations [Line Items]
Issued notes, aggregate principal amount | AUD														AUD 200
Debt instrument, maturity year							2025	2025	2025
Subordinated floating rate notes, margin				3.50%
Outstanding debt redeemed | AUD							AUD 90
Early redemption fee				$ 2,000,000

[1] For the year ended December 31, 2015, (gains) losses on the early extinguishment of debt were adjusted for the portion attributable to noncontrolling interests of $1 million.