Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Aug. 31, 2012	Aug. 31, 2011
Cash flows from operating activities:
Net loss	$ (66,677)	$ (192,679)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in (income) loss of unconsolidated joint ventures	(2,171)	56,241
Loss on loan guaranty	0	37,330
Gain on sale of operating property	0	(8,825)
Inventory impairments and land option contract abandonments	22,912	23,507
Change in assets and liabilities:
Receivables	(4,502)	(10,940)
Inventories	(10,562)	(177,770)
Accounts payable, accrued expenses and other liabilities	(31,266)	(46,953)
Other, net	16,466	10,150
Net cash used in operating activities	(75,800)	(309,939)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	2,865	(1,974)
Proceeds from sale of operating property	0	80,600
Sales (purchases) of property and equipment, net	(1,052)	(74)
Net cash provided by investing activities	1,813	78,552
Cash flows from financing activities:
Change in restricted cash	18,368	2,291
Proceeds from issuance of senior notes	694,831	0
Payment of senior notes issuance costs	(12,195)	0
Repayment on senior notes	(592,645)	(100,000)
Payments on mortgages and land contracts due to land sellers and other loans	(21,099)	(86,064)
Issuance of common stock under employee stock plans	451	1,426
Payments of cash dividends	(8,674)	(14,423)
Intercompany	0	0
Net cash provided by (used in) financing activities	79,037	(196,770)
Net increase (decrease) in cash and cash equivalents	5,050	(428,157)
Cash and cash equivalents at beginning of period	418,074	908,430
Cash and cash equivalents at end of period	423,124	480,273
KB Home Corporate
Cash flows from operating activities:
Net loss	(66,677)	(192,679)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in (income) loss of unconsolidated joint ventures	0	0
Loss on loan guaranty		0
Gain on sale of operating property		0
Inventory impairments and land option contract abandonments	0	0
Change in assets and liabilities:
Receivables	(26,660)	77,094
Inventories	0	0
Accounts payable, accrued expenses and other liabilities	(347)	(3,127)
Other, net	9,796	6,566
Net cash used in operating activities	(83,888)	(112,146)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	0	0
Proceeds from sale of operating property		0
Sales (purchases) of property and equipment, net	(65)	(178)
Net cash provided by investing activities	(65)	(178)
Cash flows from financing activities:
Change in restricted cash	18,368	23,692
Proceeds from issuance of senior notes	694,831
Payment of senior notes issuance costs	(12,195)
Repayment on senior notes	(592,645)	(100,000)
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Issuance of common stock under employee stock plans	451	1,426
Payments of cash dividends	(8,674)	(14,423)
Intercompany	3,687	(146,568)
Net cash provided by (used in) financing activities	103,823	(235,873)
Net increase (decrease) in cash and cash equivalents	19,870	(348,197)
Cash and cash equivalents at beginning of period	340,957	770,603
Cash and cash equivalents at end of period	360,827	422,406
Guarantor Subsidiaries
Cash flows from operating activities:
Net loss	(42,802)	(23,989)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in (income) loss of unconsolidated joint ventures	585	5
Loss on loan guaranty		0
Gain on sale of operating property		(8,825)
Inventory impairments and land option contract abandonments	19,510	991
Change in assets and liabilities:
Receivables	3,792	(4,247)
Inventories	29,590	(49,142)
Accounts payable, accrued expenses and other liabilities	(22,682)	(19,985)
Other, net	441	(2,989)
Net cash used in operating activities	(11,566)	(108,181)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	3,201	(1,334)
Proceeds from sale of operating property		80,600
Sales (purchases) of property and equipment, net	(652)	(81)
Net cash provided by investing activities	2,549	79,185
Cash flows from financing activities:
Change in restricted cash	0	0
Proceeds from issuance of senior notes	0
Payment of senior notes issuance costs	0
Repayment on senior notes	0	0
Payments on mortgages and land contracts due to land sellers and other loans	(20,815)	(84,638)
Issuance of common stock under employee stock plans	0	0
Payments of cash dividends	0	0
Intercompany	29,518	123,481
Net cash provided by (used in) financing activities	8,703	38,843
Net increase (decrease) in cash and cash equivalents	(314)	9,847
Cash and cash equivalents at beginning of period	32,876	3,619
Cash and cash equivalents at end of period	32,562	13,466
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net loss	(17,353)	(166,985)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in (income) loss of unconsolidated joint ventures	(2,756)	56,236
Loss on loan guaranty		37,330
Gain on sale of operating property		0
Inventory impairments and land option contract abandonments	3,402	22,516
Change in assets and liabilities:
Receivables	18,366	(83,787)
Inventories	(40,152)	(128,628)
Accounts payable, accrued expenses and other liabilities	(8,237)	(23,841)
Other, net	6,229	6,573
Net cash used in operating activities	(40,501)	(280,586)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	(336)	(640)
Proceeds from sale of operating property		0
Sales (purchases) of property and equipment, net	(335)	185
Net cash provided by investing activities	(671)	(455)
Cash flows from financing activities:
Change in restricted cash	0	(21,401)
Proceeds from issuance of senior notes	0
Payment of senior notes issuance costs	0
Repayment on senior notes	0	0
Payments on mortgages and land contracts due to land sellers and other loans	(284)	(1,426)
Issuance of common stock under employee stock plans	0	0
Payments of cash dividends	0	0
Intercompany	26,950	214,061
Net cash provided by (used in) financing activities	26,666	191,234
Net increase (decrease) in cash and cash equivalents	(14,506)	(89,807)
Cash and cash equivalents at beginning of period	44,241	134,208
Cash and cash equivalents at end of period	29,735	44,401
Consolidating Adjustments
Cash flows from operating activities:
Net loss	60,155	190,974
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in (income) loss of unconsolidated joint ventures	0	0
Loss on loan guaranty		0
Gain on sale of operating property		0
Inventory impairments and land option contract abandonments	0	0
Change in assets and liabilities:
Receivables	0	0
Inventories	0	0
Accounts payable, accrued expenses and other liabilities	0	0
Other, net	0	0
Net cash used in operating activities	60,155	190,974
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	0	0
Proceeds from sale of operating property		0
Sales (purchases) of property and equipment, net	0	0
Net cash provided by investing activities	0	0
Cash flows from financing activities:
Change in restricted cash	0	0
Proceeds from issuance of senior notes	0
Payment of senior notes issuance costs	0
Repayment on senior notes	0	0
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Issuance of common stock under employee stock plans	0	0
Payments of cash dividends	0	0
Intercompany	(60,155)	(190,974)
Net cash provided by (used in) financing activities	(60,155)	(190,974)
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	$ 0	$ 0