Supplemental Guarantor Information (Condensed Consolidated Statements of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Aug. 31, 2013		Aug. 31, 2012		Aug. 31, 2013		Aug. 31, 2012
Condensed Consolidated Statements of Operations
Revenues	$ 548,974		$ 424,504		$ 1,478,599		$ 981,914
Homebuilding:
Revenues	545,800		421,555		1,470,404		974,055
Construction and land costs	(446,381)		(351,356)		(1,232,644)		(836,229)
Selling, general and administrative expenses	(63,456)		(59,332)		(192,652)		(173,644)
Operating income (loss)	35,963		10,867		45,108		(35,818)
Interest income	193		117		629		363
Interest expense	(11,326)	[1]	(23,060)	[1]	(41,073)	[1]	(53,815)	[1]
Equity in income (loss) of unconsolidated joint ventures					(577)		2,171
Total pretax income (loss)	26,578		(7,439)		10,047		(81,477)
Income tax benefit	700		10,700		1,800		14,800
Equity in Net Income (Loss) of Subsidiaries	0		0		0		0
Net income (loss)	27,278		3,261		11,847		(66,677)
KB Home Corporate
Condensed Consolidated Statements of Operations
Revenues	0		0		0		0
Homebuilding:
Revenues	0		0		0		0
Construction and land costs	0		0		0		0
Selling, general and administrative expenses	(11,203)		(16,546)		(45,355)		(45,480)
Operating income (loss)	(11,203)		(16,546)		(45,355)		(45,480)
Interest income	178		107		607		332
Interest expense	19,646		6,096		49,253		37,026
Equity in income (loss) of unconsolidated joint ventures					0		0
Total pretax income (loss)	8,621		(10,343)		4,505		(8,122)
Income tax benefit	200		14,900		800		1,600
Equity in Net Income (Loss) of Subsidiaries	18,457		(1,296)		6,542		(60,155)
Net income (loss)	27,278		3,261		11,847		(66,677)
Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	480,069		380,165		1,306,981		869,357
Homebuilding:
Revenues	480,069		380,165		1,306,981		869,357
Construction and land costs	(390,567)		(313,469)		(1,092,603)		(746,456)
Selling, general and administrative expenses	(43,691)		(37,705)		(122,817)		(107,471)
Operating income (loss)	45,811		28,991		91,561		15,430
Interest income	15		(1,925)		17		5
Interest expense	(28,778)		(27,616)		(85,644)		(86,597)
Equity in income (loss) of unconsolidated joint ventures					(1,655)		(35)
Total pretax income (loss)	16,391		(273)		4,278		(71,198)
Income tax benefit	500		400		800		12,800
Equity in Net Income (Loss) of Subsidiaries	0		0		0		0
Net income (loss)	16,891		127		5,078		(58,398)
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	68,905		44,339		171,618		112,557
Homebuilding:
Revenues	65,731		41,390		163,423		104,698
Construction and land costs	(55,814)		(37,887)		(140,041)		(89,773)
Selling, general and administrative expenses	(8,562)		(5,081)		(24,480)		(20,693)
Operating income (loss)	1,355		(1,578)		(1,098)		(5,768)
Interest income	0		1,935		5		26
Interest expense	(2,194)		(1,540)		(4,682)		(4,244)
Equity in income (loss) of unconsolidated joint ventures					1,078		2,206
Total pretax income (loss)	1,566		3,177		1,264		(2,157)
Income tax benefit	0		(4,600)		200		400
Equity in Net Income (Loss) of Subsidiaries	0		0		0		0
Net income (loss)	1,566		(1,423)		1,464		(1,757)
Consolidating Adjustments
Condensed Consolidated Statements of Operations
Revenues	0		0		0		0
Homebuilding:
Revenues	0		0		0		0
Construction and land costs	0		0		0		0
Selling, general and administrative expenses	0		0		0		0
Operating income (loss)	0		0		0		0
Interest income	0		0		0		0
Interest expense	0		0		0		0
Equity in income (loss) of unconsolidated joint ventures					0		0
Total pretax income (loss)	0		0		0		0
Income tax benefit	0		0		0		0
Equity in Net Income (Loss) of Subsidiaries	(18,457)		1,296		(6,542)		60,155
Net income (loss)	(18,457)		1,296		(6,542)		60,155
Homebuilding [Member]
Condensed Consolidated Statements of Operations
Revenues	545,800		421,555		1,470,404		974,055
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(656)		278		(1,658)		(37)
Total pretax income (loss)	24,174		(11,798)		3,006		(89,307)
Homebuilding [Member] | KB Home Corporate
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	0		0		0		0
Total pretax income (loss)	8,621		(10,343)		4,505		(8,122)
Homebuilding [Member] | Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(657)		277		(1,656)		(36)
Total pretax income (loss)	16,391		(273)		4,278		(71,198)
Homebuilding [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	1		1		(2)		(1)
Total pretax income (loss)	(838)		(1,182)		(5,777)		(9,987)
Homebuilding [Member] | Consolidating Adjustments
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	0		0		0		0
Total pretax income (loss)	0		0		0		0
Financial services [Member]
Condensed Consolidated Statements of Operations
Revenues	3,174		2,949		8,195		7,859
Homebuilding:
Operating income (loss)	2,410		2,240		5,960		5,622
Equity in income (loss) of unconsolidated joint ventures	(6)		2,119		1,081		2,208
Total pretax income (loss)	2,404		4,359		7,041		7,830
Financial services [Member] | KB Home Corporate
Homebuilding:
Total pretax income (loss)	0		0		0		0
Financial services [Member] | Guarantor Subsidiaries
Homebuilding:
Total pretax income (loss)	0		0		0		0
Financial services [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Total pretax income (loss)	2,404		4,359		7,041		7,830
Financial services [Member] | Consolidating Adjustments
Homebuilding:
Total pretax income (loss)	$ 0		$ 0		$ 0		$ 0

[1] Amounts for the three months and nine months ended August 31, 2012 include losses on the early extinguishment of debt of $8.3 million and $10.3 million, respectively.