Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Aug. 31, 2013	Aug. 31, 2012
Cash flows from operating activities:
Net income (loss)	$ 11,847	$ (66,677)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in income (loss) of unconsolidated joint ventures	577	(2,171)
Inventory impairments and land option contract abandonments	284	22,912
Change in assets and liabilities:
Receivables	(7,001)	(4,502)
Inventories	(491,002)	(10,562)
Accounts payable, accrued expenses and other liabilities	72,315	(31,266)
Other, net	11,521	16,466
Net cash used in operating activities	(401,459)	(75,800)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(10,056)	2,865
Purchases of property and equipment, net	(1,359)	(1,052)
Net cash provided by (used in) investing activities	(11,415)	1,813
Cash flows from financing activities:
Change in restricted cash	731	18,368
Proceeds from issuance of debt	230,000	694,831
Payment of debt issuance costs	(10,086)	(12,195)
Repayment on senior notes		(592,645)
Payments on mortgages and land contracts due to land sellers and other loans	(44,405)	(21,099)
Proceeds from issuance of common stock, net	109,503	0
Issuance of common stock under employee stock plans	2,147	451
Payments of cash dividends	(6,272)	(8,674)
Stock repurchases	(7,967)	0
Intercompany	0	0
Net cash provided by (used in) financing activities	273,651	79,037
Net increase (decrease) in cash and cash equivalents	(139,223)	5,050
Cash and cash equivalents at beginning of period	525,688	418,074
Cash and cash equivalents at end of period	386,465	423,124
KB Home Corporate
Cash flows from operating activities:
Net income (loss)	11,847	(66,677)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in income (loss) of unconsolidated joint ventures	0	0
Inventory impairments and land option contract abandonments	0	0
Change in assets and liabilities:
Receivables	(46)	(26,660)
Inventories	0	0
Accounts payable, accrued expenses and other liabilities	10,505	(347)
Other, net	9,893	9,796
Net cash used in operating activities	32,199	(83,888)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	0	0
Purchases of property and equipment, net	(346)	(65)
Net cash provided by (used in) investing activities	(346)	(65)
Cash flows from financing activities:
Change in restricted cash	731	18,368
Proceeds from issuance of debt	230,000	694,831
Payment of debt issuance costs	(10,086)	(12,195)
Repayment on senior notes		(592,645)
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Proceeds from issuance of common stock, net	109,503
Issuance of common stock under employee stock plans	2,147	451
Payments of cash dividends	(6,272)	(8,674)
Stock repurchases	(7,967)
Intercompany	(499,961)	3,687
Net cash provided by (used in) financing activities	(181,905)	103,823
Net increase (decrease) in cash and cash equivalents	(150,052)	19,870
Cash and cash equivalents at beginning of period	457,007	340,957
Cash and cash equivalents at end of period	306,955	360,827
Guarantor Subsidiaries
Cash flows from operating activities:
Net income (loss)	5,078	(58,398)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in income (loss) of unconsolidated joint ventures	1,655	35
Inventory impairments and land option contract abandonments	284	22,912
Change in assets and liabilities:
Receivables	(7,119)	(1,577)
Inventories	(445,791)	10,157
Accounts payable, accrued expenses and other liabilities	50,534	(17,309)
Other, net	1,304	539
Net cash used in operating activities	(394,055)	(43,641)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(5,064)	3,801
Purchases of property and equipment, net	(735)	(989)
Net cash provided by (used in) investing activities	(5,799)	2,812
Cash flows from financing activities:
Change in restricted cash	0	0
Proceeds from issuance of debt	0	0
Payment of debt issuance costs	0	0
Repayment on senior notes		0
Payments on mortgages and land contracts due to land sellers and other loans	(44,405)	(21,099)
Proceeds from issuance of common stock, net	0
Issuance of common stock under employee stock plans	0	0
Payments of cash dividends	0	0
Stock repurchases	0
Intercompany	455,294	58,590
Net cash provided by (used in) financing activities	410,889	37,491
Net increase (decrease) in cash and cash equivalents	11,035	(3,338)
Cash and cash equivalents at beginning of period	52,933	46,375
Cash and cash equivalents at end of period	63,968	43,037
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net income (loss)	1,464	(1,757)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in income (loss) of unconsolidated joint ventures	(1,078)	(2,206)
Inventory impairments and land option contract abandonments	0	0
Change in assets and liabilities:
Receivables	164	23,735
Inventories	(45,211)	(20,719)
Accounts payable, accrued expenses and other liabilities	11,276	(13,610)
Other, net	324	6,131
Net cash used in operating activities	(33,061)	(8,426)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(4,992)	(936)
Purchases of property and equipment, net	(278)	2
Net cash provided by (used in) investing activities	(5,270)	(934)
Cash flows from financing activities:
Change in restricted cash	0	0
Proceeds from issuance of debt	0	0
Payment of debt issuance costs	0	0
Repayment on senior notes		0
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Proceeds from issuance of common stock, net	0
Issuance of common stock under employee stock plans	0	0
Payments of cash dividends	0	0
Stock repurchases	0
Intercompany	38,125	(2,122)
Net cash provided by (used in) financing activities	38,125	(2,122)
Net increase (decrease) in cash and cash equivalents	(206)	(11,482)
Cash and cash equivalents at beginning of period	15,748	30,742
Cash and cash equivalents at end of period	15,542	19,260
Consolidating Adjustments
Cash flows from operating activities:
Net income (loss)	(6,542)	60,155
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in income (loss) of unconsolidated joint ventures	0	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	(6,542)	60,155
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	0	0
Purchases of property and equipment, net	0	0
Net cash provided by (used in) investing activities	0	0
Cash flows from financing activities:
Change in restricted cash	0	0
Proceeds from issuance of debt	0	0
Payment of debt issuance costs	0	0
Repayment on senior notes		0
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Proceeds from issuance of common stock, net	0
Issuance of common stock under employee stock plans	0	0
Payments of cash dividends	0	0
Stock repurchases	0
Intercompany	6,542	(60,155)
Net cash provided by (used in) financing activities	6,542	(60,155)
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