Supplemental Guarantor Information (Condensed Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2016	May 31, 2015
Condensed Consolidated Statements of Operations
Revenues	$ 811,050	$ 622,969	$ 1,489,421	$ 1,203,090
Homebuilding:
Revenues	808,462	620,804	1,484,204	1,198,692
Construction and land costs	(688,714)	(524,410)	(1,257,532)	(1,016,828)
Selling, general and administrative expenses	(93,810)	(78,532)	(181,742)	(149,604)
Operating income (loss)	25,938	17,862	44,930	32,260
Interest income	134	152	286	255
Interest expense	(1,970)	(8,118)	(5,667)	(13,456)
Intercompany Interest Income (Expense)	0	0	0	0
Equity in income (loss) of unconsolidated joint ventures			(2,212)	1,607
Total pretax income (loss)	24,797	12,673	40,824	23,172
Income tax expense	(9,200)	(3,100)	(12,100)	(5,800)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	15,597	9,573	28,724	17,372
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	(18,976)	(19,674)	(43,316)	(35,346)
Operating income (loss)	(18,976)	(19,674)	(43,316)	(35,346)
Interest income	106	150	240	251
Interest expense	(44,337)	(47,710)	(88,707)	(91,253)
Intercompany Interest Income (Expense)	75,719	73,751	149,762	144,184
Total pretax income (loss)	12,512	6,517	17,979	17,836
Income tax expense	(2,800)	(1,200)	(2,100)	(3,400)
Income (Loss) from Subsidiaries, Net of Tax	5,885	4,256	12,845	2,936
Net income	15,597	9,573	28,724	17,372
Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	704,282	541,328	1,305,625	1,052,324
Homebuilding:
Revenues	704,282	541,328	1,305,625	1,052,324
Construction and land costs	(590,425)	(452,616)	(1,092,291)	(882,949)
Selling, general and administrative expenses	(63,206)	(48,665)	(116,342)	(94,290)
Operating income (loss)	50,651	40,047	96,992	75,085
Interest income	24	1	42	4
Interest expense	(1,921)	(1,489)	(3,802)	(2,949)
Intercompany Interest Income (Expense)	(28,086)	(28,388)	(56,149)	(55,025)
Total pretax income (loss)	19,846	9,762	35,658	16,359
Income tax expense	(8,100)	(2,500)	(11,700)	(4,300)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	11,746	7,262	23,958	12,059
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	106,768	81,641	183,796	150,766
Homebuilding:
Revenues	104,180	79,476	178,579	146,368
Construction and land costs	(98,289)	(71,794)	(165,241)	(133,879)
Selling, general and administrative expenses	(11,628)	(10,193)	(22,084)	(19,968)
Operating income (loss)	(5,737)	(2,511)	(8,746)	(7,479)
Interest income	4	1	4	0
Interest expense	0	0	0	0
Intercompany Interest Income (Expense)	(3,345)	(4,282)	(6,771)	(8,413)
Total pretax income (loss)	(7,561)	(3,606)	(12,813)	(11,023)
Income tax expense	1,700	600	1,700	1,900
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	(5,861)	(3,006)	(11,113)	(9,123)
Homebuilding [Member]
Condensed Consolidated Statements of Operations
Revenues	808,462	620,804	1,484,204	1,198,692
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(825)	(411)	(1,428)	(758)
Total pretax income (loss)	23,277	9,485	38,121	18,301
Homebuilding [Member] | KB Home Corporate
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	0	0	0	0
Total pretax income (loss)	12,512	6,517	17,979	17,836
Homebuilding [Member] | Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(822)	(409)	(1,425)	(756)
Total pretax income (loss)	19,846	9,762	35,658	16,359
Homebuilding [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(3)	(2)	(3)	(2)
Total pretax income (loss)	(9,081)	(6,794)	(15,516)	(15,894)
Financial services [Member]
Condensed Consolidated Statements of Operations
Revenues	2,588	2,165	5,217	4,398
Homebuilding:
Operating income (loss)	1,717	1,237	3,487	2,506
Equity in income (loss) of unconsolidated joint ventures	(197)	1,951	(784)	2,365
Total pretax income (loss)	1,520	3,188	2,703	4,871
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)	1,520	3,188	2,703	4,871
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	44,288	41,081	86,842	80,746
Intercompany Interest Income (Expense)	(44,288)	(41,081)	(86,842)	(80,746)
Total pretax income (loss)	0	0	0	0
Income tax expense	0	0	0	0
Income (Loss) from Subsidiaries, Net of Tax	(5,885)	(4,256)	(12,845)	(2,936)
Net income	(5,885)	(4,256)	(12,845)	(2,936)
Consolidating Adjustments | Homebuilding [Member]
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	0	0	0	0
Total pretax income (loss)	0	0	0	0
Consolidating Adjustments | Financial services [Member]
Homebuilding:
Total pretax income (loss)	$ 0	$ 0	$ 0	$ 0