Supplemental Guarantor Information (Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	May. 31, 2015	Nov. 30, 2014	May. 31, 2014	Nov. 30, 2013
Assets
Cash and Cash Equivalents, at Carrying Value	$ 442,088	$ 358,768	$ 487,270	$ 532,523
Restricted cash	27,213	27,235
Receivables	151,578	125,488
Inventory, Operative Builders	3,393,672	3,218,387
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	77,935	79,441
Deferred tax assets, net	819,532	825,232
Other assets	117,745	114,915
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	5,039,060	4,757,550
Due from Affiliates	0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	601,729	582,598
Mortgages and notes payable	2,819,510	2,576,525
Financial services	1,985	2,517
Due to Affiliate	0	0
Stockholders' equity	1,615,836	1,595,910
Total liabilities and stockholders’ equity	5,039,060	4,757,550
KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value	374,375	303,280	412,811	476,847
Restricted cash	27,213	27,235
Receivables	49	15
Inventory, Operative Builders	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	216,592	215,923
Other assets	102,173	99,099
Investments in and Advances to Affiliates, Amount of Equity	39,500	39,356
Total assets	4,528,336	4,267,520
Due from Affiliates	3,768,434	3,582,612
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	130,086	138,298
Mortgages and notes payable	2,763,907	2,513,165
Financial services	0	0
Due to Affiliate	18,507	20,147
Stockholders' equity	1,615,836	1,595,910
Total liabilities and stockholders’ equity	4,528,336	4,267,520
Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	59,410	38,124	64,027	39,952
Restricted cash	0	0
Receivables	148,316	123,024
Inventory, Operative Builders	3,144,547	2,980,056
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	77,935	79,441
Deferred tax assets, net	546,046	552,653
Other assets	13,605	13,922
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	3,989,859	3,787,220
Due from Affiliates	0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	370,824	331,361
Mortgages and notes payable	55,603	63,360
Financial services	0	0
Due to Affiliate	3,563,432	3,392,499
Stockholders' equity	0	0
Total liabilities and stockholders’ equity	3,989,859	3,787,220
Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	8,303	17,364	10,432	15,724
Restricted cash	0	0
Receivables	3,213	2,449
Inventory, Operative Builders	249,125	238,331
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	56,894	56,656
Other assets	1,967	1,894
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	433,580	437,697
Due from Affiliates	104,781	112,919
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	100,819	112,939
Mortgages and notes payable	0	0
Financial services	1,985	2,517
Due to Affiliate	291,276	282,885
Stockholders' equity	39,500	39,356
Total liabilities and stockholders’ equity	433,580	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	(39,500)	(39,356)
Total assets	(3,912,715)	(3,734,887)
Due from Affiliates	(3,873,215)	(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	(3,873,215)	(3,695,531)
Stockholders' equity	(39,500)	(39,356)
Total liabilities and stockholders’ equity	(3,912,715)	(3,734,887)
Homebuilding [Member]
Assets
Cash and Cash Equivalents, at Carrying Value	439,920	356,366	484,472
Total assets	5,027,595	4,747,064
Liabilities and stockholders' equity
Total Liabilities Homebuilding	3,421,239	3,159,123
Homebuilding [Member] | KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value	374,375	303,280
Total assets	720,402	645,552
Liabilities and stockholders' equity
Total Liabilities Homebuilding	2,893,993	2,651,463
Homebuilding [Member] | Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	59,410	38,124
Total assets	3,989,859	3,787,220
Liabilities and stockholders' equity
Total Liabilities Homebuilding	426,427	394,721
Homebuilding [Member] | Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	6,135	14,962
Total assets	317,334	314,292
Liabilities and stockholders' equity
Total Liabilities Homebuilding	100,819	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	2,168	2,402	$ 2,798
Receivables	681	1,738
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	8,514	6,149
Other assets	102	197
Total assets	11,465	10,486
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	1,985	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	11,465	10,486
Financial services [Member] | Consolidating Adjustments
Assets
Total assets	$ 0	$ 0