Supplemental Guarantor Information (Condensed Consolidated Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Feb. 28, 2015	Nov. 30, 2014	Feb. 28, 2014	Nov. 30, 2013
Assets
Cash and Cash Equivalents, at Carrying Value	$ 548,079	$ 358,768	$ 306,450	$ 532,523
Restricted cash	27,984	27,235
Receivables	143,697	125,488
Inventory, Operative Builders	3,246,383	3,218,387
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	73,502	79,441
Deferred tax assets, net	822,632	825,232
Other assets	119,873	114,915
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	4,989,857	4,757,550
Due from Affiliates	0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	559,147	582,598
Mortgages and notes payable	2,824,170	2,576,525
Financial services	1,970	2,517
Due to Affiliate	0	0
Stockholders' equity	1,604,570	1,595,910
Total liabilities and stockholders’ equity	4,989,857	4,757,550
KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value	469,030	303,280	234,234	476,847
Restricted cash	27,984	27,235
Receivables	293	15
Inventory, Operative Builders	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	216,092	215,923
Other assets	104,420	99,099
Investments in and Advances to Affiliates, Amount of Equity	37,488	39,356
Total assets	4,518,907	4,267,520
Due from Affiliates	3,660,500	3,582,612
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	131,682	138,298
Mortgages and notes payable	2,763,532	2,513,165
Financial services	0	0
Due to Affiliate	19,123	20,147
Stockholders' equity	1,604,570	1,595,910
Total liabilities and stockholders’ equity	4,518,907	4,267,520
Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	69,405	38,124	57,749	39,952
Restricted cash	0	0
Receivables	140,849	123,024
Inventory, Operative Builders	2,999,424	2,980,056
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	73,502	79,441
Deferred tax assets, net	549,546	552,653
Other assets	13,558	13,922
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	3,843,184	3,787,220
Due from Affiliates	0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	327,964	331,361
Mortgages and notes payable	60,638	63,360
Financial services	0	0
Due to Affiliate	3,453,262	3,392,499
Stockholders' equity	1,320	0
Total liabilities and stockholders’ equity	3,843,184	3,787,220
Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	9,644	17,364	14,467	15,724
Restricted cash	0	0
Receivables	2,555	2,449
Inventory, Operative Builders	246,959	238,331
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	56,994	56,656
Other assets	1,895	1,894
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	434,883	437,697
Due from Affiliates	109,129	112,919
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	99,501	112,939
Mortgages and notes payable	0	0
Financial services	1,970	2,517
Due to Affiliate	297,244	282,885
Stockholders' equity	36,168	39,356
Total liabilities and stockholders’ equity	434,883	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	(37,488)	(39,356)
Total assets	(3,807,117)	(3,734,887)
Due from Affiliates	(3,769,629)	(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	(3,769,629)	(3,695,531)
Stockholders' equity	(37,488)	(39,356)
Total liabilities and stockholders’ equity	(3,807,117)	(3,734,887)
Homebuilding [Member]
Assets
Cash and Cash Equivalents, at Carrying Value	545,641	356,366	303,269
Total assets	4,979,712	4,747,064
Liabilities and stockholders' equity
Total Liabilities Homebuilding	3,383,317	3,159,123
Homebuilding [Member] | KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value	472,130	303,280
Total assets	820,919	645,552
Liabilities and stockholders' equity
Total Liabilities Homebuilding	2,895,214	2,651,463
Homebuilding [Member] | Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	66,305	38,124
Total assets	3,843,184	3,787,220
Liabilities and stockholders' equity
Total Liabilities Homebuilding	388,602	394,721
Homebuilding [Member] | Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	7,206	14,962
Total assets	315,609	314,292
Liabilities and stockholders' equity
Total Liabilities Homebuilding	99,501	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	2,438	2,402	3,181
Receivables	1,024	1,738
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	6,563	6,149
Other assets	120	197
Total assets	10,145	10,486
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	1,970	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	10,145	10,486
Financial services [Member] | Consolidating Adjustments
Assets
Total assets	$ 0	$ 0