| Document and Entity Information | May 25, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | May 25, 2021 |
| Document Fiscal Year Focus | 2021 |
| Entity Registrant Name | KB HOME |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-9195 |
| Entity Tax Identification Number | 95-3666267 |
| Entity Address, Address Line One | 10990 Wilshire Boulevard |
| Entity Address, City or Town | Los Angeles |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 90024 |
| City Area Code | 310 |
| Local Phone Number | 231-4000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000795266 |
| Amendment Flag | false |
| Document Fiscal Year Focus | FY |
| Common Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock (par value $1.00 per share) |
| Trading Symbol | KBH |
| Security Exchange Name | NYSE |
| Rights [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Rights to Purchase Series A Participating Cumulative Preferred Stock |
| Security Exchange Name | NYSE |
| No Trading Symbol Flag | true |
