Supplemental Guarantor Information (Condensed Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2015	May. 31, 2014
Condensed Consolidated Statements of Operations
Revenues	$ 622,969	$ 565,007	$ 1,203,090	$ 1,015,694
Homebuilding:
Revenues	620,804	562,396	1,198,692	1,010,663
Construction and land costs	(524,410)	(456,560)	(1,016,828)	(825,834)
Selling, general and administrative expenses	(78,532)	(71,544)	(149,604)	(132,818)
Operating income (loss)	17,862	34,292	32,260	52,011
Interest income	152	115	255	283
Interest expense	(8,118)	(8,558)	(13,456)	(19,834)
Intercompany Interest Income (Expense)	0	0	0	0
Equity in income (loss) of unconsolidated joint ventures			1,607	1,900
Total pretax income (loss)	12,673	26,924	23,172	37,687
Income tax expense	(3,100)	(300)	(5,800)	(500)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	9,573	26,624	17,372	37,187
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	(19,674)	(15,751)	(35,346)	(31,495)
Operating income (loss)	(19,674)	(15,751)	(35,346)	(31,495)
Interest income	150	109	251	276
Interest expense	(47,710)	(41,671)	(91,253)	(79,679)
Intercompany Interest Income (Expense)	73,751	70,709	144,184	130,431
Total pretax income (loss)	6,517	13,396	17,836	19,533
Income tax expense	(1,200)	(50)	(3,400)	(50)
Income (Loss) from Subsidiaries, Net of Tax	4,256	13,278	2,936	17,704
Net income	9,573	26,624	17,372	37,187
Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	569,956	515,045	1,104,232	907,223
Homebuilding:
Revenues	569,956	515,045	1,104,232	907,223
Construction and land costs	(477,129)	(416,412)	(928,269)	(737,764)
Selling, general and administrative expenses	(51,764)	(46,709)	(100,269)	(83,790)
Operating income (loss)	41,063	51,924	75,694	85,669
Interest income	1	5	4	6
Interest expense	(1,489)	(1,488)	(2,949)	(2,760)
Intercompany Interest Income (Expense)	(30,172)	(33,275)	(58,577)	(63,349)
Total pretax income (loss)	8,994	16,488	13,414	18,185
Income tax expense	(2,300)	(200)	(3,600)	(400)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	6,694	16,288	9,814	17,785
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues	53,013	49,962	98,858	108,471
Homebuilding:
Revenues	50,848	47,351	94,460	103,440
Construction and land costs	(47,281)	(40,148)	(88,559)	(88,070)
Selling, general and administrative expenses	(7,094)	(9,084)	(13,989)	(17,533)
Operating income (loss)	(3,527)	(1,881)	(8,088)	(2,163)
Interest income	1	1	0	1
Interest expense	0	0	0	0
Intercompany Interest Income (Expense)	(2,498)	(2,833)	(4,861)	(4,477)
Total pretax income (loss)	(2,838)	(2,960)	(8,078)	(31)
Income tax expense	400	(50)	1,200	(50)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
Net income	(2,438)	(3,010)	(6,878)	(81)
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	41,081	34,601	80,746	62,605
Intercompany Interest Income (Expense)	(41,081)	(34,601)	(80,746)	(62,605)
Total pretax income (loss)	0	0	0	0
Income tax expense	0	0	0	0
Income (Loss) from Subsidiaries, Net of Tax	(4,256)	(13,278)	(2,936)	(17,704)
Net income	(4,256)	(13,278)	(2,936)	(17,704)
Homebuilding [Member]
Condensed Consolidated Statements of Operations
Revenues	620,804	562,396	1,198,692	1,010,663
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(411)	(678)	(758)	1,912
Total pretax income (loss)	9,485	25,171	18,301	34,372
Homebuilding [Member] | KB Home Corporate
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	0	0	0	0
Total pretax income (loss)	6,517	13,396	17,836	19,533
Homebuilding [Member] | Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(409)	(678)	(758)	(1,381)
Total pretax income (loss)	8,994	16,488	13,414	18,185
Homebuilding [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures	(2)	0	0	3,293
Total pretax income (loss)	(6,026)	(4,713)	(12,949)	(3,346)
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	2,165	2,611	4,398	5,031
Homebuilding:
Operating income (loss)	1,237	1,759	2,506	3,327
Equity in income (loss) of unconsolidated joint ventures	1,951	(6)	2,365	(12)
Total pretax income (loss)	3,188	1,753	4,871	3,315
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)	3,188	1,753	4,871	3,315
Financial services [Member] | Consolidating Adjustments
Homebuilding:
Total pretax income (loss)	$ 0	$ 0	$ 0	$ 0