Supplemental Guarantor Information (Condensed Consolidated Statements of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	May 31, 2013		May 31, 2012		May 31, 2013		May 31, 2012
Condensed Consolidated Statements of Operations
Revenues	$ 524,406		$ 302,852		$ 929,625		$ 557,410
Homebuilding:
Revenues	521,788		300,605		924,604		552,500
Construction and land costs	(442,998)		(253,041)		(786,263)		(484,873)
Selling, general and administrative expenses	(70,099)		(63,100)		(129,196)		(114,312)
Operating income (loss)	8,691		(15,536)		9,145		(46,685)
Interest income	232		111		436		246
Interest expense	(14,507)	[1]	(14,469)	[1]	(29,747)	[1]	(30,755)	[1]
Equity in income (loss) of unconsolidated joint ventures					85		(226)
Total pretax income (loss)	(4,173)		(28,636)		(16,531)		(74,038)
Income tax benefit	1,200		4,500		1,100		4,100
Equity in net loss of subsidiaries	0		0		0		0
Net loss	(2,973)		(24,136)		(15,431)		(69,938)
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	(19,329)		(14,934)		(34,152)		(28,934)
Operating income (loss)	(19,329)		(14,934)		(34,152)		(28,934)
Interest income	228		100		429		225
Interest expense	16,098		16,810		29,607		30,930
Equity in income (loss) of unconsolidated joint ventures					0		0
Total pretax income (loss)	(3,003)		1,976		(4,116)		2,221
Income tax benefit	1,000		(200)		300		(100)
Equity in net loss of subsidiaries	(970)		(25,912)		(11,615)		(72,059)
Net loss	(2,973)		(24,136)		(15,431)		(69,938)
Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	465,388		265,273		826,912		489,192
Homebuilding:
Revenues	465,388		265,273		826,912		489,192
Construction and land costs	(394,639)		(224,404)		(702,036)		(435,800)
Selling, general and administrative expenses	(42,462)		(41,384)		(79,126)		(66,468)
Operating income (loss)	28,287		(515)		45,750		(13,076)
Interest income	2		3		2		4
Interest expense	(28,823)		(29,408)		(56,866)		(59,194)
Equity in income (loss) of unconsolidated joint ventures					(999)		(313)
Total pretax income (loss)	(1,098)		(30,161)		(12,113)		(72,579)
Income tax benefit	200		4,600		800		4,100
Equity in net loss of subsidiaries	0		0		0		0
Net loss	(898)		(25,561)		(11,313)		(68,479)
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	59,018		37,579		102,713		68,218
Homebuilding:
Revenues	56,400		35,332		97,692		63,308
Construction and land costs	(48,359)		(28,637)		(84,227)		(49,073)
Selling, general and administrative expenses	(8,308)		(6,782)		(15,918)		(18,910)
Operating income (loss)	(267)		(87)		(2,453)		(4,675)
Interest income	2		8		5		17
Interest expense	(1,782)		(1,871)		(2,488)		(2,491)
Equity in income (loss) of unconsolidated joint ventures					1,084		87
Total pretax income (loss)	(72)		(451)		(302)		(3,680)
Income tax benefit	0		100		0		100
Equity in net loss of subsidiaries	0		0		0		0
Net loss	(72)		(351)		(302)		(3,580)
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 loss of subsidiaries	970		25,912		11,615		72,059
Net loss	970		25,912		11,615		72,059
Homebuilding [Member]
Condensed Consolidated Statements of Operations
Revenues	521,788		300,605		924,604		552,500
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(567)		(243)		(1,002)		(315)
Total pretax income (loss)	(6,151)		(30,137)		(21,168)		(77,509)
Homebuilding [Member] | KB Home Corporate
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	0		0		0		0
Total pretax income (loss)	(3,003)		1,976		(4,116)		2,221
Homebuilding [Member] | Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(564)		(241)		(999)		(313)
Total pretax income (loss)	(1,098)		(30,161)		(12,113)		(72,579)
Homebuilding [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(3)		(2)		(3)		(2)
Total pretax income (loss)	(2,050)		(1,952)		(4,939)		(7,151)
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	2,618		2,247		5,021		4,910
Homebuilding:
Operating income (loss)	1,982		1,554		3,550		3,382
Equity in income (loss) of unconsolidated joint ventures	(4)		(53)		1,087		89
Total pretax income (loss)	1,978		1,501		4,637		3,471
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)	1,978		1,501		4,637		3,471
Financial services [Member] | Consolidating Adjustments
Homebuilding:
Total pretax income (loss)	$ 0		$ 0		$ 0		$ 0

[1] Amounts for the six months ended May 31, 2012 include a $2.0 million loss on the early extinguishment of debt.