Supplemental Guarantor Information (Condensed Consolidating Statements of Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2011
Condensed Statement of Income Captions [Line Items]
Net income (loss)	$ 28,116	$ 27,278	$ (2,973)	$ (12,458)	$ 7,724	$ 3,261	$ (24,136)	$ (45,802)	$ 39,963	$ (58,953)	$ (178,768)
Postretirement benefits adjustment									10,442	(1,806)	(3,495)
Other comprehensive income									10,442	(1,806)	(3,495)
Comprehensive income (loss)									50,405	(60,759)	(182,263)
KB Home Corporate
Condensed Statement of Income Captions [Line Items]
Net income (loss)									39,963	(58,953)	(178,768)
Postretirement benefits adjustment									10,442	(1,806)	(3,495)
Other comprehensive income									10,442	(1,806)	(3,495)
Comprehensive income (loss)									50,405	(60,759)	(182,263)
Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income (loss)									40,603	(51,342)	(182,922)
Postretirement benefits adjustment									0	0	0
Other comprehensive income									0	0	0
Comprehensive income (loss)									40,603	(51,342)	(182,922)
Non-Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income (loss)									(57)	(176)	4,266
Postretirement benefits adjustment									0	0	0
Other comprehensive income									0	0	0
Comprehensive income (loss)									(57)	(176)	4,266
Consolidating Adjustments
Condensed Statement of Income Captions [Line Items]
Net income (loss)									(40,546)	51,518	178,656
Postretirement benefits adjustment									0	0	0
Other comprehensive income									0	0	0
Comprehensive income (loss)									$ (40,546)	$ 51,518	$ 178,656