Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	May 31, 2013	May 31, 2012
Cash flows from operating activities:
Net loss	$ (15,431)	$ (69,938)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in income (loss) of unconsolidated joint ventures	(85)	226
Inventory impairments and land option contract abandonments	284	16,509
Change in assets and liabilities:
Receivables	(405)	16,795
Inventories	(290,661)	(16,131)
Accounts payable, accrued expenses and other liabilities	32,210	(40,214)
Other, net	6,488	2,872
Net cash used in operating activities	(267,600)	(89,881)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(5,651)	4,550
Purchases of property and equipment, net	(752)	(592)
Net cash provided by (used in) investing activities	(6,403)	3,958
Cash flows from financing activities:
Change in restricted cash	40	1,299
Proceeds from issuance of debt	230,000	344,831
Payment of debt issuance costs	(10,086)	(6,751)
Repayment on senior notes		(340,481)
Payments on mortgages and land contracts due to land sellers and other loans	(37,830)	(6,695)
Proceeds from issuance of common stock, net	109,503	0
Issuance of common stock under employee stock plans	2,106	353
Payments of cash dividends	(4,179)	(6,746)
Stock repurchases	(33)	0
Intercompany	0	0
Net cash provided by (used in) financing activities	289,521	(14,190)
Net increase (decrease) in cash and cash equivalents	15,518	(100,113)
Cash and cash equivalents at beginning of period	525,688	418,074
Cash and cash equivalents at end of period	541,206	317,961
KB Home Corporate
Cash flows from operating activities:
Net loss	(15,431)	(69,938)
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	52	(98)
Inventories	0	0
Accounts payable, accrued expenses and other liabilities	6,816	(4,198)
Other, net	4,473	(499)
Net cash used in operating activities	(4,090)	(74,733)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	0	0
Purchases of property and equipment, net	(166)	(53)
Net cash provided by (used in) investing activities	(166)	(53)
Cash flows from financing activities:
Change in restricted cash	40	1,293
Proceeds from issuance of debt	230,000	344,831
Payment of debt issuance costs	(10,086)	(6,751)
Repayment on senior notes		(340,481)
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	2,106	353
Payments of cash dividends	(4,179)	(6,746)
Stock repurchases	(33)
Intercompany	(299,447)	14,642
Net cash provided by (used in) financing activities	27,904	7,141
Net increase (decrease) in cash and cash equivalents	23,648	(67,645)
Cash and cash equivalents at beginning of period	457,007	340,957
Cash and cash equivalents at end of period	480,655	273,312
Guarantor Subsidiaries
Cash flows from operating activities:
Net loss	(11,313)	(68,479)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in income (loss) of unconsolidated joint ventures	999	313
Inventory impairments and land option contract abandonments	284	11,764
Change in assets and liabilities:
Receivables	(977)	(2,605)
Inventories	(249,342)	1,287
Accounts payable, accrued expenses and other liabilities	22,577	(23,587)
Other, net	1,341	372
Net cash used in operating activities	(236,431)	(80,935)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(659)	4,552
Purchases of property and equipment, net	(517)	(550)
Net cash provided by (used in) investing activities	(1,176)	4,002
Cash flows from financing activities:
Change in restricted cash	0	6
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	(37,830)	(6,695)
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	271,940	62,739
Net cash provided by (used in) financing activities	234,110	56,050
Net increase (decrease) in cash and cash equivalents	(3,497)	(20,883)
Cash and cash equivalents at beginning of period	52,933	46,375
Cash and cash equivalents at end of period	49,436	25,492
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net loss	(302)	(3,580)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in income (loss) of unconsolidated joint ventures	(1,084)	(87)
Inventory impairments and land option contract abandonments	0	4,745
Change in assets and liabilities:
Receivables	520	19,498
Inventories	(41,319)	(17,418)
Accounts payable, accrued expenses and other liabilities	2,817	(12,429)
Other, net	674	2,999
Net cash used in operating activities	(38,694)	(6,272)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(4,992)	(2)
Purchases of property and equipment, net	(69)	11
Net cash provided by (used in) investing activities	(5,061)	9
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	39,122	(5,322)
Net cash provided by (used in) financing activities	39,122	(5,322)
Net increase (decrease) in cash and cash equivalents	(4,633)	(11,585)
Cash and cash equivalents at beginning of period	15,748	30,742
Cash and cash equivalents at end of period	11,115	19,157
Consolidating Adjustments
Cash flows from operating activities:
Net loss	11,615	72,059
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	11,615	72,059
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	(11,615)	(72,059)
Net cash provided by (used in) financing activities	(11,615)	(72,059)
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