Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Feb. 28, 2013	Feb. 29, 2012	Feb. 28, 2013 KB Home Corporate	Feb. 29, 2012 KB Home Corporate	Feb. 28, 2013 Guarantor Subsidiaries	Feb. 29, 2012 Guarantor Subsidiaries	Feb. 28, 2013 Non-Guarantor Subsidiaries	Feb. 29, 2012 Non-Guarantor Subsidiaries	Feb. 28, 2013 Consolidating Adjustments	Feb. 29, 2012 Consolidating Adjustments
Cash flows from operating activities:
Net loss	$ (12,458)	$ (45,802)	$ (12,458)	$ (45,802)	$ (5,042)	$ (33,897)	$ (6,303)	$ (12,150)	$ 11,345	$ 46,047
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in (income) loss of unconsolidated joint ventures	(656)	(70)	0	0	558	51	(1,214)	(121)	0	0
Inventory impairments	0	6,572		0		6,572		0		0
Change in assets and liabilities:
Receivables	326	18,293	30	(19)	(1,321)	(2,119)	1,617	20,431	0	0
Inventories	(198,761)	(25,856)	0	0	(57,554)	(12,997)	(141,207)	(12,859)	0	0
Accounts payable, accrued expenses and other liabilities	(2,413)	(60,621)	8,010	(9,889)	(8,413)	(31,936)	(2,010)	(18,796)	0	0
Other, net	2,930	(2,100)	1,281	(5,390)	540	189	1,109	3,101	0	0
Net cash used in operating activities	(211,032)	(109,584)	(3,137)	(61,100)	(71,232)	(74,137)	(148,008)	(20,394)	11,345	46,047
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(304)	6,547	0	0	(314)	6,549	10	(2)	0	0
Purchases of property and equipment, net	(430)	(429)	(96)	(21)	(129)	(149)	(205)	(259)	0	0
Net cash provided by (used in) investing activities	(734)	6,118	(96)	(21)	(443)	6,400	(195)	(261)	0	0
Cash flows from financing activities:
Change in restricted cash	(2,257)	591	(2,257)	591	0	0	0	0	0	0
Proceeds from issuance of debt	230,000	344,831	230,000	344,831	0	0	0	0	0	0
Payment of debt issuance costs	(6,878)	(5,816)	(6,878)	(5,816)	0	0	0	0	0	0
Repayment on senior notes		(340,481)		(340,481)		0		0		0
Payments on mortgages and land contracts due to land sellers and other loans	(17,003)	(1,715)	0	0	(5,678)	(1,644)	(11,325)	(71)	0	0
Proceeds from issuance of common stock, net	109,811	0	109,811		0		0		0
Issuance of common stock under employee stock plans	52	175	52	175	0	0	0	0	0	0
Payments of cash dividends	(2,089)	(4,818)	(2,089)	(4,818)	0	0	0	0	0	0
Intercompany	0	0	(227,866)	(14,899)	83,336	60,890	155,875	56	(11,345)	(46,047)
Net cash provided by (used in) financing activities	311,636	(7,233)	100,773	(20,417)	77,658	59,246	144,550	(15)	(11,345)	(46,047)
Net increase (decrease) in cash and cash equivalents	99,870	(110,699)	97,540	(81,538)	5,983	(8,491)	(3,653)	(20,670)	0	0
Cash and cash equivalents at beginning of period	525,688	418,074	457,007	340,957	22,642		46,039		0	0
Cash and cash equivalents at end of period	$ 625,558	$ 307,375	$ 554,547	$ 259,419	$ 28,625	$ 24,385	$ 42,386	$ 23,571	$ 0	$ 0