Supplemental Guarantor Information (Condensed Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2015	Aug. 31, 2014
Condensed Consolidated Statements of Operations
Revenues	$ 843,157	$ 589,214	$ 2,046,247	$ 1,604,908
Homebuilding:
Revenues	840,204	586,231	2,038,896	1,596,894
Construction and land costs	(709,148)	(479,424)	(1,725,976)	(1,305,258)
Selling, general and administrative expenses	(95,074)	(72,897)	(244,678)	(205,715)
Operating income (loss)	35,982	33,910	68,242	85,921
Interest income	87	110	342	393
Interest expense	(4,394)	(6,455)	(17,850)	(26,289)
Intercompany Interest Income (Expense)	0	0	0	0
Equity in income (loss) of unconsolidated joint ventures			1,843	872
Total pretax income (loss)	33,954	28,661	57,126	66,348
Income tax expense	(10,700)	(300)	(16,500)	(800)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	23,254	28,361	40,626	65,548
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	(28,540)	(15,995)	(63,886)	(47,489)
Operating income (loss)	(28,540)	(15,995)	(63,886)	(47,489)
Interest income	86	109	337	385
Interest expense	(45,040)	(42,955)	(136,292)	(122,634)
Intercompany Interest Income (Expense)	74,501	76,512	218,684	206,943
Total pretax income (loss)	1,007	17,671	18,843	37,205
Income tax expense	2,200	(50)	2,900	(100)
Income (Loss) from Subsidiaries, Net of Tax	20,047	10,740	18,883	28,443
Net income	23,254	28,361	40,626	65,548
Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	761,783	529,599	1,866,015	1,436,822
Homebuilding:
Revenues	761,783	529,599	1,866,015	1,436,822
Construction and land costs	(638,451)	(429,998)	(1,566,720)	(1,167,762)
Selling, general and administrative expenses	(58,137)	(47,653)	(158,403)	(131,443)
Operating income (loss)	65,195	51,948	140,892	137,617
Interest income	1	1	3	7
Interest expense	(1,547)	(1,648)	(4,497)	(4,408)
Intercompany Interest Income (Expense)	(30,203)	(35,728)	(88,780)	(99,077)
Total pretax income (loss)	33,024	13,822	46,438	32,007
Income tax expense	(12,100)	(200)	(18,700)	(600)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	20,924	13,622	27,738	31,407
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	81,374	59,615	180,232	168,086
Homebuilding:
Revenues	78,421	56,632	172,881	160,072
Construction and land costs	(70,697)	(49,426)	(159,256)	(137,496)
Selling, general and administrative expenses	(8,397)	(9,249)	(22,389)	(26,783)
Operating income (loss)	(673)	(2,043)	(8,764)	(4,207)
Interest income	0	0	2	1
Interest expense	0	0	0	0
Intercompany Interest Income (Expense)	(2,105)	(2,636)	(6,965)	(7,113)
Total pretax income (loss)	(77)	(2,832)	(8,155)	(2,864)
Income tax expense	(800)	(50)	(700)	(100)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	(877)	(2,882)	(8,855)	(2,964)
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	42,193	38,148	122,939	100,753
Intercompany Interest Income (Expense)	(42,193)	(38,148)	(122,939)	(100,753)
Total pretax income (loss)	0	0	0	0
Income tax expense	0	0	0	0
Income (Loss) from Subsidiaries, Net of Tax	(20,047)	(10,740)	(18,883)	(28,443)
Net income	(20,047)	(10,740)	(18,883)	(28,443)
Homebuilding [Member]
Condensed Consolidated Statements of Operations
Revenues	840,204	586,231	2,038,896	1,596,894
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(422)	(751)	(1,180)	1,161
Total pretax income (loss)	31,253	26,814	49,554	61,186
Homebuilding [Member] | KB Home Corporate
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	0	0	0	0
Total pretax income (loss)	1,007	17,671	18,843	37,205
Homebuilding [Member] | Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(422)	(751)	(1,180)	(2,132)
Total pretax income (loss)	33,024	13,822	46,438	32,007
Homebuilding [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	0	0	0	3,293
Total pretax income (loss)	(2,778)	(4,679)	(15,727)	(8,026)
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	2,953	2,983	7,351	8,014
Homebuilding:
Operating income (loss)	2,043	2,124	4,549	5,451
Equity in income (loss) of unconsolidated joint ventures	658	(277)	3,023	(289)
Total pretax income (loss)	2,701	1,847	7,572	5,162
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)	2,701	1,847	7,572	5,162
Financial services [Member] | Consolidating Adjustments
Homebuilding:
Total pretax income (loss)	$ 0	$ 0	$ 0	$ 0