| Document and Entity Information | Sep. 30, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | GENWORTH FINANCIAL INC |
| Amendment Flag | false |
| Entity Central Index Key | 0001276520 |
| Document Type | 8-K |
| Document Period End Date | Sep. 30, 2020 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-32195 |
| Entity Tax Identification Number | 80-0873306 |
| Entity Address, Address Line One | 6620 West Broad Street |
| Entity Address, City or Town | Richmond |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 23230 |
| City Area Code | (804) |
| Local Phone Number | 281-6000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Class A Common Stock, par value $.001 per share |
| Trading Symbol | GNW |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
