Document and Entity Information - USD ($)	12 Months Ended
	Nov. 30, 2018	Dec. 31, 2018	May 31, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	KB Home
Entity Central Index Key	0000795266
Document Type	10-K
Document Period End Date	Nov. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--11-30
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 2,532,566,398
Entity Common Stock Shares Outstanding		86,925,192