Supplemental Guarantor Information (Condensed Consolidating Statements of Operations) (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 Consolidated Statements of Operations
Revenues	$ 618,531	$ 548,974	$ 524,406	$ 405,219	$ 578,201	$ 424,504	$ 302,852	$ 254,558	$ 2,097,130		$ 1,560,115		$ 1,315,866
Homebuilding:
Revenues									2,084,978		1,548,432		1,305,562
Construction and land costs									(1,737,086)		(1,332,045)		(1,157,280)
Selling, general and administrative expenses									(255,808)		(236,643)		(220,591)
Loss on loan guaranty									0		0		(30,765)
Operating income (loss)									92,084		(20,256)		(103,074)
Interest income									792		518		871
Interest Expense									(62,690)	[1]	(69,804)	[1]	(49,204)	[1]
Intercompany interest									0		0		0
Equity in income (loss) of unconsolidated joint ventures									(933)		1,797		(36,553)
Pretax income (loss)	28,316	26,578	(4,173)	(12,358)	2,424	(7,439)	(28,636)	(45,402)	38,363		(79,053)		(181,168)
Income tax benefit									1,600		20,100		2,400
Equity in net loss of subsidiaries									0		0		0
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)
KB Home Corporate
Condensed Consolidated Statements of Operations
Revenues									0		0		0
Homebuilding:
Revenues									0		0		0
Construction and land costs									0		0		0
Selling, general and administrative expenses									(60,545)		(60,101)		(52,784)
Loss on loan guaranty													0
Operating income (loss)									(60,545)		(60,101)		(52,784)
Interest income									768		480		715
Interest Expense									(143,902)		(127,291)		(110,068)
Intercompany interest									(203,096)		(176,977)		(162,025)
Equity in income (loss) of unconsolidated joint ventures									0		0
Pretax income (loss)									(583)		(9,935)		(112)
Income tax benefit									0		2,500		0
Equity in net loss of subsidiaries									40,546		(51,518)		(178,656)
Net income (loss)									39,963		(58,953)		(178,768)
Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues									2,036,340		1,506,333		1,262,453
Homebuilding:
Revenues									2,036,340		1,506,333		1,262,453
Construction and land costs									(1,692,525)		(1,291,877)		(1,108,572)
Selling, general and administrative expenses									(180,344)		(163,266)		(151,916)
Loss on loan guaranty													(30,765)
Operating income (loss)									163,471		51,190		(28,800)
Interest income									18		13		48
Interest Expense									(5,199)		(5,365)		(3,007)
Intercompany interest									(117,180)		(114,286)		(97,623)
Equity in income (loss) of unconsolidated joint ventures									(2,007)		(394)
Pretax income (loss)									39,103		(68,842)		(185,222)
Income tax benefit									1,500		17,500		2,300
Equity in net loss of subsidiaries									0		0		0
Net income (loss)									40,603		(51,342)		(182,922)
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues									60,790		53,782		53,413
Homebuilding:
Revenues									48,638		42,099		43,109
Construction and land costs									(44,561)		(40,168)		(48,708)
Selling, general and administrative expenses									(14,919)		(13,276)		(15,891)
Loss on loan guaranty													0
Operating income (loss)									(10,842)		(11,345)		(21,490)
Interest income									6		25		108
Interest Expense									0		0		(1,038)
Intercompany interest									(495)		(161)		(1,569)
Equity in income (loss) of unconsolidated joint ventures									0		0
Pretax income (loss)									(157)		(276)		4,166
Income tax benefit									100		100		100
Equity in net loss of subsidiaries									0		0		0
Net income (loss)									(57)		(176)		4,266
Consolidating Adjustments
Condensed Consolidated Statements of Operations
Revenues									0		0		0
Homebuilding:
Revenues									0		0		0
Construction and land costs									0		0		0
Selling, general and administrative expenses									0		0		0
Loss on loan guaranty													0
Operating income (loss)									0		0		0
Interest income									0		0		0
Interest Expense									(86,411)		(62,852)		(62,833)
Intercompany interest									(86,411)		(62,852)		(62,833)
Equity in income (loss) of unconsolidated joint ventures									0		0
Pretax income (loss)									0		0		0
Income tax benefit									0		0		0
Equity in net loss of subsidiaries									(40,546)		51,518		178,656
Net income (loss)									(40,546)		51,518		178,656
Homebuilding [Member]
Condensed Consolidated Statements of Operations
Revenues									2,084,978		1,548,432		1,305,562
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures									(2,007)		(394)		(55,839)
Pretax income (loss)									28,179		(89,936)		(207,246)
Homebuilding [Member] | KB Home Corporate
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures													0
Pretax income (loss)									(583)		(9,935)		(112)
Homebuilding [Member] | Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures													(55,840)
Pretax income (loss)									39,103		(68,842)		(185,222)
Homebuilding [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures													1
Pretax income (loss)									(10,341)		(11,159)		(21,912)
Homebuilding [Member] | Consolidating Adjustments
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures													0
Pretax income (loss)									0		0		0
Financial services [Member]
Condensed Consolidated Statements of Operations
Revenues									12,152		11,683		10,304
Homebuilding:
Operating income (loss)									9,110		8,692		6,792
Equity in income (loss) of unconsolidated joint ventures									1,074		2,191		19,286
Pretax income (loss)									10,184		10,883		26,078
Financial services [Member] | KB Home Corporate
Homebuilding:
Pretax income (loss)									0		0		0
Financial services [Member] | Guarantor Subsidiaries
Homebuilding:
Pretax income (loss)									0		0		0
Financial services [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Pretax income (loss)									10,184		10,883		26,078
Financial services [Member] | Consolidating Adjustments
Homebuilding:
Pretax income (loss)									$ 0		$ 0		$ 0

[1] Amounts for the years ended November 30, 2013 and 2012 included losses on the early extinguishment of debt of $10.4 million and $10.3 million, respectively. Amounts for the year ended November 30, 2011 included a gain on the early extinguishment of secured debt of $3.6 million