Supplemental Guarantor Information (Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Aug. 31, 2015	Nov. 30, 2014	Aug. 31, 2014	Nov. 30, 2013
Assets
Cash and Cash Equivalents, at Carrying Value	$ 354,879	$ 358,768	$ 299,008	$ 532,523
Restricted cash	25,028	27,235
Receivables	159,576	125,488
Inventory, Operative Builders	3,401,737	3,218,387
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	72,800	79,441
Deferred tax assets, net	810,016	825,232
Other assets	114,352	114,915
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	4,948,496	4,757,550
Due from Affiliates	0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	675,762	582,598
Mortgages and notes payable	2,630,732	2,576,525
Financial services	1,776	2,517
Due to Affiliate	0	0
Stockholders' equity	1,640,226	1,595,910
Total liabilities and stockholders’ equity	4,948,496	4,757,550
KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value	288,869	303,280	236,649	476,847
Restricted cash	25,028	27,235
Receivables	284	15
Inventory, Operative Builders	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	218,954	215,923
Other assets	98,917	99,099
Investments in and Advances to Affiliates, Amount of Equity	71,219	39,356
Total assets	4,367,215	4,267,520
Due from Affiliates	3,663,944	3,582,612
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	144,782	138,298
Mortgages and notes payable	2,564,378	2,513,165
Financial services	0	0
Due to Affiliate	17,829	20,147
Stockholders' equity	1,640,226	1,595,910
Total liabilities and stockholders’ equity	4,367,215	4,267,520
Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	60,271	38,124	53,787	39,952
Restricted cash	0	0
Receivables	156,354	123,024
Inventory, Operative Builders	3,163,292	2,980,056
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	72,800	79,441
Deferred tax assets, net	534,728	552,653
Other assets	13,448	13,922
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	4,000,893	3,787,220
Due from Affiliates	0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	426,452	331,361
Mortgages and notes payable	66,354	63,360
Financial services	0	0
Due to Affiliate	3,475,060	3,392,499
Stockholders' equity	33,027	0
Total liabilities and stockholders’ equity	4,000,893	3,787,220
Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	5,739	17,364	8,572	15,724
Restricted cash	0	0
Receivables	2,938	2,449
Inventory, Operative Builders	238,445	238,331
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	56,334	56,656
Other assets	1,987	1,894
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	419,857	437,697
Due from Affiliates	104,306	112,919
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	104,528	112,939
Mortgages and notes payable	0	0
Financial services	1,776	2,517
Due to Affiliate	275,361	282,885
Stockholders' equity	38,192	39,356
Total liabilities and stockholders’ equity	419,857	437,697
Consolidating Adjustments
Assets
Cash and Cash Equivalents, at Carrying Value	0	0	0	$ 0
Restricted cash	0	0
Receivables	0	0
Inventory, Operative Builders	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	0	0
Other assets	0	0
Investments in and Advances to Affiliates, Amount of Equity	(71,219)	(39,356)
Total assets	(3,839,469)	(3,734,887)
Due from Affiliates	(3,768,250)	(3,695,531)
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	0	0
Mortgages and notes payable	0	0
Financial services	0	0
Due to Affiliate	(3,768,250)	(3,695,531)
Stockholders' equity	(71,219)	(39,356)
Total liabilities and stockholders’ equity	(3,839,469)	(3,734,887)
Homebuilding [Member]
Assets
Cash and Cash Equivalents, at Carrying Value	352,952	356,366	297,058
Total assets	4,936,461	4,747,064
Liabilities and stockholders' equity
Total Liabilities Homebuilding	3,306,494	3,159,123
Homebuilding [Member] | KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value	288,869	303,280
Total assets	632,052	645,552
Liabilities and stockholders' equity
Total Liabilities Homebuilding	2,709,160	2,651,463
Homebuilding [Member] | Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	60,271	38,124
Total assets	4,000,893	3,787,220
Liabilities and stockholders' equity
Total Liabilities Homebuilding	492,806	394,721
Homebuilding [Member] | Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	3,812	14,962
Total assets	303,516	314,292
Liabilities and stockholders' equity
Total Liabilities Homebuilding	104,528	112,939
Homebuilding [Member] | Consolidating Adjustments
Assets
Cash and Cash Equivalents, at Carrying Value	0	0
Total assets	0	0
Liabilities and stockholders' equity
Total Liabilities Homebuilding	0	0
Financial services [Member]
Assets
Cash and Cash Equivalents, at Carrying Value	1,927	2,402	$ 1,950
Receivables	846	1,738
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	9,171	6,149
Other assets	91	197
Total assets	12,035	10,486
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	1,776	2,517
Financial services [Member] | KB Home Corporate
Assets
Total assets	0	0
Financial services [Member] | Guarantor Subsidiaries
Assets
Total assets	0	0
Financial services [Member] | Non-Guarantor Subsidiaries
Assets
Total assets	12,035	10,486
Financial services [Member] | Consolidating Adjustments
Assets
Total assets	$ 0	$ 0