Supplemental Guarantor Information (Condensed Consolidated Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Feb. 28, 2013	Nov. 30, 2012	Feb. 29, 2012	Nov. 30, 2011
Assets
Cash and cash equivalents	$ 624,044	$ 524,765
Restricted cash	44,619	42,362
Receivables	65,630	64,821
Inventories	1,937,774	1,706,571
Investments in unconsolidated joint ventures	123,210	123,674
Other assets	102,578	95,050
Total homebuilding assets	2,897,855	2,557,243
Financial services	2,782	4,455
Investments in subsidiaries	0	0
Total assets	2,900,637	2,561,698
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	461,455	458,889
Mortgages and notes payable	1,963,753	1,722,815
Total homebuilding liabilities	2,425,208	2,181,704
Financial services	2,294	3,188
Intercompany	0	0
Stockholders' equity	473,135	376,806	393,868	442,657
Total liabilities and stockholders’ equity	2,900,637	2,561,698
KB Home Corporate
Assets
Cash and cash equivalents	554,547	457,007
Restricted cash	44,619	42,362
Receivables	91	121
Inventories	0	0
Investments in unconsolidated joint ventures	0	0
Other assets	93,196	85,901
Total homebuilding assets	692,453	585,391
Financial services	0	0
Investments in subsidiaries	(2,947)	11,411
Total assets	689,506	596,802
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	142,672	134,314
Mortgages and notes payable	1,875,735	1,645,394
Total homebuilding liabilities	2,018,407	1,779,708
Financial services	0	0
Intercompany	(1,802,036)	(1,559,712)
Stockholders' equity	473,135	376,806
Total liabilities and stockholders’ equity	689,506	596,802
Guarantor Subsidiaries
Assets
Cash and cash equivalents	28,625	22,642
Restricted cash	0	0
Receivables	50,839	49,518
Inventories	1,132,565	1,075,011
Investments in unconsolidated joint ventures	109,102	109,346
Other assets	7,075	7,491
Total homebuilding assets	1,328,206	1,264,008
Financial services	0	0
Investments in subsidiaries	0	0
Total assets	1,328,206	1,264,008
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	139,150	147,563
Mortgages and notes payable	63,918	69,596
Total homebuilding liabilities	203,068	217,159
Financial services	0	0
Intercompany	1,130,180	1,046,849
Stockholders' equity	(5,042)	0
Total liabilities and stockholders’ equity	1,328,206	1,264,008
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	40,872	45,116
Restricted cash	0	0
Receivables	14,700	15,182
Inventories	805,209	631,560
Investments in unconsolidated joint ventures	14,108	14,328
Other assets	2,307	1,658
Total homebuilding assets	877,196	707,844
Financial services	2,782	4,455
Investments in subsidiaries	0	0
Total assets	879,978	712,299
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	179,633	177,012
Mortgages and notes payable	24,100	7,825
Total homebuilding liabilities	203,733	184,837
Financial services	2,294	3,188
Intercompany	671,856	512,863
Stockholders' equity	2,095	11,411
Total liabilities and stockholders’ equity	879,978	712,299
Consolidating Adjustments
Assets
Cash and cash equivalents	0	0
Restricted cash	0	0
Receivables	0	0
Inventories	0	0
Investments in unconsolidated joint ventures	0	0
Other assets	0	0
Total homebuilding assets	0	0
Financial services	0	0
Investments in subsidiaries	2,947	(11,411)
Total assets	2,947	(11,411)
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	0	0
Mortgages and notes payable	0	0
Total homebuilding liabilities	0	0
Financial services	0	0
Intercompany	0	0
Stockholders' equity	2,947	(11,411)
Total liabilities and stockholders’ equity	$ 2,947	$ (11,411)