Supplemental Guarantor Information (Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands		Aug. 31, 2017	Nov. 30, 2016	Aug. 31, 2016	Nov. 30, 2015
Assets
Cash and Cash Equivalents, at Carrying Value		$ 494,807	$ 593,000	$ 337,722	$ 560,341
Receivables		229,033	231,665
Inventory, Operative Builders		3,513,794	3,403,228
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		64,513	64,016
Deferred tax assets, net		683,085	738,985
Other assets		102,394	91,145
Investments in and Advances to Affiliates, Amount of Equity		0	0
Total assets		5,099,559	5,131,624
Due from Affiliates		0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities		754,703	766,327
Mortgages and notes payable		2,502,379	2,640,149
Financial services		1,535	2,003
Due to Affiliate		0	0
Stockholders' equity		1,840,942	1,723,145
Total liabilities and stockholders’ equity		5,099,559	5,131,624
KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value		400,956	463,100	272,694	444,850
Receivables		4,939	4,807
Inventory, Operative Builders		0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		0	0
Deferred tax assets, net		271,967	276,737
Other assets		91,420	79,526
Investments in and Advances to Affiliates, Amount of Equity		108,984	35,965
Total assets		4,484,795	4,419,147
Due from Affiliates		3,606,529	3,559,012
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities		169,661	131,530
Mortgages and notes payable		2,453,127	2,548,112
Financial services		0	0
Due to Affiliate		21,065	16,360
Stockholders' equity		1,840,942	1,723,145
Total liabilities and stockholders’ equity		4,484,795	4,419,147
Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value		82,622	100,439	57,955	96,741
Receivables		144,447	135,915
Inventory, Operative Builders		3,167,657	3,048,132
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		62,011	61,517
Deferred tax assets, net		265,640	318,077
Other assets		8,384	9,177
Investments in and Advances to Affiliates, Amount of Equity		0	0
Total assets		3,730,761	3,673,257
Due from Affiliates		0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities		365,102	397,605
Mortgages and notes payable		23,222	66,927
Financial services		0	0
Due to Affiliate		3,270,731	3,208,725
Stockholders' equity		71,706	0
Total liabilities and stockholders’ equity		3,730,761	3,673,257
Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value		11,229	29,461	7,073	18,750
Receivables		79,647	90,943
Inventory, Operative Builders		346,137	355,096
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		2,502	2,499
Deferred tax assets, net		145,478	144,171
Other assets		2,590	2,442
Investments in and Advances to Affiliates, Amount of Equity		0	0
Total assets		701,851	731,259
Due from Affiliates		102,335	97,062
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities		219,940	237,192
Mortgages and notes payable		26,030	25,110
Financial services		1,535	2,003
Due to Affiliate		417,068	430,989
Stockholders' equity		37,278	35,965
Total liabilities and stockholders’ equity		701,851	731,259
Homebuilding [Member]
Assets
Cash and Cash Equivalents, at Carrying Value		494,053	592,086	334,669
Total assets		5,086,872	5,121,125
Liabilities and stockholders' equity
Total Liabilities Homebuilding		3,257,082	3,406,476
Homebuilding [Member] | KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value		400,956	463,100
Total assets		769,282	824,170
Liabilities and stockholders' equity
Total Liabilities Homebuilding		2,622,788	2,679,642
Homebuilding [Member] | Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value		82,622	100,439
Total assets		3,730,761	3,673,257
Liabilities and stockholders' equity
Total Liabilities Homebuilding		388,324	464,532
Homebuilding [Member] | Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value		10,475	28,547
Total assets		586,829	623,698
Liabilities and stockholders' equity
Total Liabilities Homebuilding		245,970	262,302
Financial services [Member]
Assets
Cash and Cash Equivalents, at Carrying Value		754	914	3,053
Receivables		2,224	1,764
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	[1]	9,631	7,771
Other assets		78	50
Total assets		12,687	10,499
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities		1,535	2,003
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		12,687	10,499
Consolidating Adjustments
Assets
Cash and Cash Equivalents, at Carrying Value		0	0	$ 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		(108,984)	(35,965)
Total assets		(3,817,848)	(3,692,039)
Due from Affiliates		(3,708,864)	(3,656,074)
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		(3,708,864)	(3,656,074)
Stockholders' equity		(108,984)	(35,965)
Total liabilities and stockholders’ equity		(3,817,848)	(3,692,039)
Consolidating Adjustments | Homebuilding [Member]
Assets
Cash and Cash Equivalents, at Carrying Value		0	0
Total assets		0	0
Liabilities and stockholders' equity
Total Liabilities Homebuilding		0	0
Consolidating Adjustments | Financial services [Member]
Assets
Total assets		$ 0	$ 0

[1] Our investments in unconsolidated joint ventures as of August 31, 2017 included a $5.3 million capital contribution we made to KBHS in the 2017 first quarter, and a $5.0 million distribution we received from HCM in the 2017 second quarter.