Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Nov. 30, 2012	Nov. 30, 2011	Nov. 30, 2010
Cash flows from operating activities:
Net loss	$ (58,953)	$ (178,768)	$ (69,368)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures	(1,797)	36,553	(772)
Loss on loan guaranty	0	30,765	0
Gain on sale of operating property	0	(8,825)	0
Inventory impairments and land option contract abandonments	28,533	25,791	19,925
Changes in assets and liabilities:
Receivables	24,994	(2,220)	211,318
Inventories	30,347	(12,345)	(129,334)
Accounts payable, accrued expenses and other liabilities	(2,143)	(253,547)	(199,205)
Other, net	13,636	15,051	33,472
Net cash provided by (used in) operating activities	34,617	(347,545)	(133,964)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	989	(67,260)	(15,669)
Proceeds from sale of operating property	0	80,600	0
Purchases of property and equipment, net	(1,749)	(242)	(420)
Net cash provided by (used in) investing activities	(760)	13,098	(16,089)
Cash flows from financing activities:
Change in restricted cash	22,119	50,996	(1,185)
Proceeds from issuance of senior notes	694,831	0	0
Payment of senior notes issuance costs	(12,445)	0	0
Repayment of senior notes	(592,645)	(100,000)	0
Payments on mortgages and land contracts due to land sellers and other loans	(26,298)	(89,461)	(101,154)
Issuance of common stock under employee stock plans	593	1,796	1,851
Excess tax benefit associated with exercise of stock options			583
Payments of cash dividends	(10,599)	(19,240)	(19,223)
Repurchases of common stock	(1,799)	0	(350)
Intercompany	0	0	0
Net cash provided by (used in) financing activities	73,757	(155,909)	(119,478)
Net increase (decrease) in cash and cash equivalents	107,614	(490,356)	(269,531)
Cash and cash equivalents at beginning of year	418,074	908,430	1,177,961
Cash and cash equivalents at end of year	525,688	418,074	908,430
KB Home Corporate
Cash flows from operating activities:
Net loss	(58,953)	(178,768)	(69,368)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures	0	0	0
Loss on loan guaranty		0
Gain on sale of operating property		0
Inventory impairments and land option contract abandonments	0	0	0
Changes in assets and liabilities:
Receivables	680	3,404	187,542
Inventories	0	0	0
Accounts payable, accrued expenses and other liabilities	11,281	(3,035)	(16,973)
Other, net	6,507	9,186	(8,461)
Net cash provided by (used in) operating activities	(40,485)	(169,213)	92,740
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	0	0	0
Proceeds from sale of operating property		0
Purchases of property and equipment, net	(175)	(200)	(229)
Net cash provided by (used in) investing activities	(175)	(200)	(229)
Cash flows from financing activities:
Change in restricted cash	22,119	24,239	25,578
Proceeds from issuance of senior notes	694,831
Payment of senior notes issuance costs	(12,445)
Repayment of senior notes	(592,645)	(100,000)
Payments on mortgages and land contracts due to land sellers and other loans	0	3,397	0
Issuance of common stock under employee stock plans	593	1,796	1,851
Excess tax benefit associated with exercise of stock options			583
Payments of cash dividends	(10,599)	(19,240)	(19,223)
Repurchases of common stock	(1,799)		(350)
Intercompany	56,655	(170,425)	(325,469)
Net cash provided by (used in) financing activities	156,710	(260,233)	(317,030)
Net increase (decrease) in cash and cash equivalents	116,050	(429,646)	(224,519)
Cash and cash equivalents at beginning of year	340,957	770,603	995,122
Cash and cash equivalents at end of year	457,007	340,957	770,603
Guarantor Subsidiaries
Cash flows from operating activities:
Net loss	(49,311)	(140,094)	(18,708)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures	983
Loss on loan guaranty		30,765
Inventory impairments and land option contract abandonments	10,417
Changes in assets and liabilities:
Receivables	(7,716)
Inventories	(59,875)
Accounts payable, accrued expenses and other liabilities	20,858
Other, net	660
Net cash provided by (used in) operating activities	(83,984)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	1,656
Purchases of property and equipment, net	(855)
Net cash provided by (used in) investing activities	801
Cash flows from financing activities:
Change in restricted cash	0
Proceeds from issuance of senior notes	0
Payment of senior notes issuance costs	0
Repayment of senior notes	0
Payments on mortgages and land contracts due to land sellers and other loans	(26,298)
Issuance of common stock under employee stock plans	0
Payments of cash dividends	0
Repurchases of common stock	0
Intercompany	103,275
Net cash provided by (used in) financing activities	76,977
Net increase (decrease) in cash and cash equivalents	(6,206)
Cash and cash equivalents at beginning of year	28,848
Cash and cash equivalents at end of year	22,642	28,848
Guarantor Subsidiaries 2011
Cash flows from operating activities:
Net loss		(140,094)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures		55,831
Loss on loan guaranty		30,765
Gain on sale of operating property		(8,825)
Inventory impairments and land option contract abandonments		21,511
Changes in assets and liabilities:
Receivables		(9,726)
Inventories		(40,973)
Accounts payable, accrued expenses and other liabilities		(247,292)
Other, net		4,277
Net cash provided by (used in) operating activities		(334,526)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures		(77,090)
Proceeds from sale of operating property		80,600
Purchases of property and equipment, net		(202)
Net cash provided by (used in) investing activities		3,308
Cash flows from financing activities:
Change in restricted cash		26,757
Repayment of senior notes		0
Payments on mortgages and land contracts due to land sellers and other loans		(87,941)
Issuance of common stock under employee stock plans		0
Payments of cash dividends		0
Intercompany		411,309
Net cash provided by (used in) financing activities		350,125
Net increase (decrease) in cash and cash equivalents		18,907
Cash and cash equivalents at beginning of year		13,969
Cash and cash equivalents at end of year		32,876
Guarantor Subsidiaries 2010
Cash flows from operating activities:
Net loss			(18,708)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures			186
Inventory impairments and land option contract abandonments			1,980
Changes in assets and liabilities:
Receivables			3,557
Inventories			(99,216)
Accounts payable, accrued expenses and other liabilities			(65,878)
Other, net			1,608
Net cash provided by (used in) operating activities			(176,471)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures			(517)
Purchases of property and equipment, net			(70)
Net cash provided by (used in) investing activities			(587)
Cash flows from financing activities:
Change in restricted cash			0
Payments on mortgages and land contracts due to land sellers and other loans			(81,041)
Issuance of common stock under employee stock plans			0
Excess tax benefit associated with exercise of stock options			0
Payments of cash dividends			0
Repurchases of common stock			0
Intercompany			217,240
Net cash provided by (used in) financing activities			136,199
Net increase (decrease) in cash and cash equivalents			(40,859)
Cash and cash equivalents at beginning of year			44,478
Cash and cash equivalents at end of year			3,619
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net loss	(2,207)	(38,562)	(8,834)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures	(2,780)
Loss on loan guaranty		0
Inventory impairments and land option contract abandonments	18,116
Changes in assets and liabilities:
Receivables	32,030
Inventories	90,222
Accounts payable, accrued expenses and other liabilities	(34,282)
Other, net	6,469
Net cash provided by (used in) operating activities	107,568
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	(667)
Purchases of property and equipment, net	(719)
Net cash provided by (used in) investing activities	(1,386)
Cash flows from financing activities:
Change in restricted cash	0
Proceeds from issuance of senior notes	0
Payment of senior notes issuance costs	0
Repayment of senior notes	0
Payments on mortgages and land contracts due to land sellers and other loans	0
Issuance of common stock under employee stock plans	0
Payments of cash dividends	0
Repurchases of common stock	0
Intercompany	(108,412)
Net cash provided by (used in) financing activities	(108,412)
Net increase (decrease) in cash and cash equivalents	(2,230)
Cash and cash equivalents at beginning of year	48,269
Cash and cash equivalents at end of year	46,039	48,269
Non-Guarantor Subsidiaries 2011
Cash flows from operating activities:
Net loss		(38,562)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures		(19,278)
Loss on loan guaranty		0
Gain on sale of operating property		0
Inventory impairments and land option contract abandonments		4,280
Changes in assets and liabilities:
Receivables		4,102
Inventories		28,628
Accounts payable, accrued expenses and other liabilities		(3,220)
Other, net		1,588
Net cash provided by (used in) operating activities		(22,462)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures		9,830
Proceeds from sale of operating property		0
Purchases of property and equipment, net		160
Net cash provided by (used in) investing activities		9,990
Cash flows from financing activities:
Change in restricted cash		0
Repayment of senior notes		0
Payments on mortgages and land contracts due to land sellers and other loans		(4,917)
Issuance of common stock under employee stock plans		0
Payments of cash dividends		0
Intercompany		(62,228)
Net cash provided by (used in) financing activities		(67,145)
Net increase (decrease) in cash and cash equivalents		(79,617)
Cash and cash equivalents at beginning of year		123,858
Cash and cash equivalents at end of year		44,241
Non-Guarantor Subsidiaries 2010
Cash flows from operating activities:
Net loss			(8,834)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures			(958)
Inventory impairments and land option contract abandonments			17,945
Changes in assets and liabilities:
Receivables			20,219
Inventories			(30,118)
Accounts payable, accrued expenses and other liabilities			(116,354)
Other, net			40,325
Net cash provided by (used in) operating activities			(77,775)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures			(15,152)
Purchases of property and equipment, net			(121)
Net cash provided by (used in) investing activities			(15,273)
Cash flows from financing activities:
Change in restricted cash			(26,763)
Payments on mortgages and land contracts due to land sellers and other loans			(20,113)
Issuance of common stock under employee stock plans			0
Excess tax benefit associated with exercise of stock options			0
Payments of cash dividends			0
Repurchases of common stock			0
Intercompany			135,771
Net cash provided by (used in) financing activities			88,895
Net increase (decrease) in cash and cash equivalents			(4,153)
Cash and cash equivalents at beginning of year			138,361
Cash and cash equivalents at end of year			134,208
Consolidating Adjustments
Cash flows from operating activities:
Net loss	51,518	178,656	27,542
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Equity in (income) loss of unconsolidated joint ventures	0	0	0
Loss on loan guaranty		0
Gain on sale of operating property		0
Inventory impairments and land option contract abandonments	0	0	0
Changes in assets and liabilities:
Receivables	0	0	0
Inventories	0	0	0
Accounts payable, accrued expenses and other liabilities	0	0	0
Other, net	0	0	0
Net cash provided by (used in) operating activities	51,518	178,656	27,542
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	0	0	0
Proceeds from sale of operating property		0
Purchases of property and equipment, net	0	0	0
Net cash provided by (used in) investing activities	0	0	0
Cash flows from financing activities:
Change in restricted cash	0	0	0
Proceeds from issuance of senior notes	0
Payment of senior notes issuance costs	0
Repayment of senior notes	0	0
Payments on mortgages and land contracts due to land sellers and other loans	0	0	0
Issuance of common stock under employee stock plans	0	0	0
Excess tax benefit associated with exercise of stock options			0
Payments of cash dividends	0	0	0
Repurchases of common stock	0		0
Intercompany	(51,518)	(178,656)	(27,542)
Net cash provided by (used in) financing activities	(51,518)	(178,656)	(27,542)
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	$ 0	$ 0	$ 0