Supplemental Guarantor Information (Condensed Consolidated Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2013	Nov. 30, 2012	May 31, 2012	Nov. 30, 2011
Assets
Cash and Cash Equivalents, at Carrying Value	$ 541,206	$ 525,688	$ 317,961	$ 418,074
Restricted cash	42,322	42,362
Receivables	66,121	64,821
Inventories	2,029,390	1,706,571
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	122,800	123,674
Other assets	103,797	95,050
Intercompany Receivables	0	0
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	2,912,121	2,561,698
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	495,953	458,889
Mortgages and notes payable	1,943,275	1,722,815
Financial services	2,077	3,188
Intercompany	0	0
Stockholders' equity	470,816	376,806	369,531	442,657
Total liabilities and stockholders’ equity	2,912,121	2,561,698
KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value	480,655	457,007	273,312	340,957
Restricted cash	42,322	42,362
Receivables	69	121
Inventories	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other assets	94,314	85,901
Intercompany Receivables	1,853,125	1,559,712
Investments in and Advances to Affiliates, Amount of Equity	17,545	11,411
Total assets	2,488,030	2,156,514
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	141,130	134,314
Mortgages and notes payable	1,876,084	1,645,394
Financial services	0	0
Intercompany	0	0
Stockholders' equity	470,816	376,806
Total liabilities and stockholders’ equity	2,488,030	2,156,514
Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	49,436	52,933	25,492	46,375
Restricted cash	0	0
Receivables	64,577	63,600
Inventories	1,849,657	1,572,999
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	120,300	114,292
Other assets	8,464	15,638
Intercompany Receivables	0	0
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	2,092,434	1,819,462
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	230,218	207,641
Mortgages and notes payable	67,191	77,421
Financial services	0	0
Intercompany	1,795,025	1,534,400
Stockholders' equity	0	0
Total liabilities and stockholders’ equity	2,092,434	1,819,462
Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	11,115	15,748	19,157	30,742
Restricted cash	0	0
Receivables	1,475	1,100
Inventories	179,733	133,572
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	2,500	9,382
Other assets	1,019	(6,489)
Intercompany Receivables	0	0
Investments in and Advances to Affiliates, Amount of Equity	0	0
Total assets	202,327	156,845
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	124,605	116,934
Mortgages and notes payable	0	0
Financial services	2,077	3,188
Intercompany	58,100	25,312
Stockholders' equity	17,545	11,411
Total liabilities and stockholders’ equity	202,327	156,845
Consolidating Adjustments
Assets
Cash and Cash Equivalents, at Carrying Value	0	0	0	0
Restricted cash	0	0
Receivables	0	0
Inventories	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other assets	0	0
Intercompany Receivables	(1,853,125)	(1,559,712)
Investments in and Advances to Affiliates, Amount of Equity	(17,545)	(11,411)
Total assets	(1,870,670)	(1,571,123)
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	0	0
Mortgages and notes payable	0	0
Financial services	0	0
Intercompany	(1,853,125)	(1,559,712)
Stockholders' equity	(17,545)	(11,411)
Total liabilities and stockholders’ equity	(1,870,670)	(1,571,123)
Homebuilding [Member]
Assets
Cash and Cash Equivalents, at Carrying Value	538,571	524,765	314,258
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	122,800	123,674
Total assets	2,903,001	2,557,243
Liabilities and stockholders' equity
Total Liabilities Homebuilding	2,439,228	2,181,704
Homebuilding [Member] | KB Home Corporate
Assets
Cash and Cash Equivalents, at Carrying Value	480,655	457,007
Total assets	617,360	585,391
Liabilities and stockholders' equity
Total Liabilities Homebuilding	2,017,214	1,779,708
Homebuilding [Member] | Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	49,436	52,933
Total assets	2,092,434	1,819,462
Liabilities and stockholders' equity
Total Liabilities Homebuilding	297,409	285,062
Homebuilding [Member] | Non-Guarantor Subsidiaries
Assets
Cash and Cash Equivalents, at Carrying Value	8,480	14,825
Total assets	193,207	152,390
Liabilities and stockholders' equity
Total Liabilities Homebuilding	124,605	116,934
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	2,635	923	3,703
Receivables	964	1,859
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	5,503	1,630
Other assets	18	43
Total assets	9,120	4,455
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	2,077	3,188
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	9,120	4,455
Financial services [Member] | Consolidating Adjustments
Assets
Total assets	$ 0	$ 0