Supplemental Guarantor Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	Aug. 31, 2010	May 31, 2010	Feb. 28, 2010	Nov. 30, 2011	Nov. 30, 2010	Nov. 30, 2009
Condensed Consolidated Statements of Operations
Revenues	$ 479,872	$ 367,316	$ 271,738	$ 196,940	$ 450,963	$ 501,003	$ 374,052	$ 263,978	$ 1,315,866	$ 1,589,996	$ 1,824,850
Homebuilding:
Revenues									1,305,562	1,581,763	1,816,415
Construction and land costs									(1,129,985)	(1,308,288)	(1,749,911)
Selling, general and administrative expenses									(247,886)	(289,520)	(303,024)
Loss on loan guaranty			(14,600)	(22,800)					(30,765)
Operating income (loss)									(103,074)	(16,045)	(236,520)
Interest income									871	2,098	7,515
Interest expense									(49,204)	(68,307)	(51,763)
Equity in loss of unconsolidated joint ventures									(55,839)	(6,257)	(49,615)
Homebuilding pretax loss									(207,246)	(88,511)	(330,383)
Financial services pretax income									26,078	12,143	19,199
Total pretax loss	11,411	(9,649)	(68,804)	(114,126)	15,442	(6,697)	(30,609)	(54,504)	(181,168)	(76,368)	(311,184)
Income tax benefit									2,400	7,000	209,400
Net loss	13,911	(9,649)	(68,504)	(114,526)	17,442	(1,397)	(30,709)	(54,704)	(178,768)	(69,368)	(101,784)
KB Home Corporate[Member]
Homebuilding:
Selling, general and administrative expenses									(52,784)	(68,149)	(71,181)
Operating income (loss)									(52,784)	(68,149)	(71,181)
Interest income									715	1,770	5,965
Interest expense									51,957	20,353	31,442
Homebuilding pretax loss									(112)	(46,026)	(33,774)
Total pretax loss									(112)	(46,026)	(33,774)
Income tax benefit									0	4,200	22,700
Equity in net loss of subsidiaries									(178,656)	(27,542)	(90,710)
Net loss									(178,768)	(69,368)	(101,784)
Guarantor Subsidiaries [Member]
Condensed Consolidated Statements of Operations
Revenues									745,965	429,917	1,608,533
Homebuilding:
Revenues									745,965	429,917	1,608,533
Construction and land costs									(638,802)	(360,450)	(1,548,678)
Selling, general and administrative expenses									(93,288)	(48,233)	(198,964)
Loss on loan guaranty									(30,765)
Operating income (loss)									(16,890)	21,234	(139,109)
Interest income									36	30	887
Interest expense									(69,309)	(41,686)	(74,946)
Equity in loss of unconsolidated joint ventures									(55,831)	(186)	(22,840)
Homebuilding pretax loss									(141,994)	(20,608)	(236,008)
Total pretax loss									(141,994)	(20,608)	(236,008)
Income tax benefit									1,900	1,900	158,800
Net loss									(140,094)	(18,708)	(77,208)
Non-Guarantor Subsidiaries [Member]
Condensed Consolidated Statements of Operations
Revenues									569,901	1,160,079	216,317
Homebuilding:
Revenues									559,597	1,151,846	207,882
Construction and land costs									(491,183)	(947,838)	(201,233)
Selling, general and administrative expenses									(101,814)	(173,138)	(32,879)
Operating income (loss)									(33,400)	30,870	(26,230)
Interest income									120	298	663
Interest expense									(31,852)	(46,974)	(8,259)
Equity in loss of unconsolidated joint ventures									(8)	(6,071)	(26,775)
Homebuilding pretax loss									(65,140)	(21,877)	(60,601)
Financial services pretax income									26,078	12,143	19,199
Total pretax loss									(39,062)	(9,734)	(41,402)
Income tax benefit									500	900	27,900
Net loss									(38,562)	(8,834)	(13,502)
Consolidating Adjustments [Member]
Homebuilding:
Equity in net loss of subsidiaries									178,656	27,542	90,170
Net loss									$ 178,656	$ 27,542	$ 90,710