Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Nov. 30, 2014	Nov. 30, 2013	Nov. 30, 2012
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	$ (630,691)	$ (443,486)	$ 34,617
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	(49,097)	(14,359)	989
Proceeds from sale of investment in unconsolidated joint venture	10,110	0	0
Purchases of property and equipment, net	(5,795)	(2,391)	(1,749)
Intercompany	0	0	0
Net cash used in investing activities	(44,782)	(16,750)	(760)
Cash flows from financing activities:
Change in restricted cash	14,671	456	22,119
Proceeds from issuance of debt	400,000	680,000	694,831
Payment of debt issuance costs	(5,448)	(16,525)	(12,445)
Repayment of senior notes	0	(225,394)	(592,645)
Payments on mortgages and land contracts due to land sellers and other loans	(36,918)	(66,296)	(26,298)
Proceeds from issuance of common stock, net	137,045	109,503	0
Issuance of common stock under employee stock plans	1,896	2,181	593
Payments of cash dividends	(8,982)	(8,366)	(10,599)
Stock repurchases	(546)	(8,488)	(1,799)
Intercompany	0	0	0
Net cash provided by financing activities	501,718	467,071	73,757
Net increase (decrease) in cash and cash equivalents	(173,755)	6,835	107,614
Cash and cash equivalents at beginning of year	532,523	525,688	418,074
Cash and cash equivalents at end of year	358,768	532,523	525,688
KB Home Corporate
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	82,629	4,795	16,433
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	0	0	0
Proceeds from sale of investment in unconsolidated joint venture	0
Purchases of property and equipment, net	(208)	(519)	(175)
Intercompany	(794,624)	(517,803)	(263)
Net cash used in investing activities	(794,832)	(518,322)	(438)
Cash flows from financing activities:
Change in restricted cash	14,671	456	22,119
Proceeds from issuance of debt	400,000	680,000	694,831
Payment of debt issuance costs	(5,448)	(16,525)	(12,445)
Repayment of senior notes		(225,394)	(592,645)
Payments on mortgages and land contracts due to land sellers and other loans	0	0	0
Proceeds from issuance of common stock, net	137,045	109,503
Issuance of common stock under employee stock plans	1,896	2,181	593
Payments of cash dividends	(8,982)	(8,366)	(10,599)
Stock repurchases	(546)	(8,488)	(1,799)
Intercompany	0	0	0
Net cash provided by financing activities	538,636	533,367	100,055
Net increase (decrease) in cash and cash equivalents	(173,567)	19,840	116,050
Cash and cash equivalents at beginning of year	476,847	457,007	340,957
Cash and cash equivalents at end of year	303,280	476,847	457,007
Guarantor Subsidiaries
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	(680,649)	(483,363)	21,233
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	(48,849)	(9,336)	1,381
Proceeds from sale of investment in unconsolidated joint venture	0
Purchases of property and equipment, net	(4,961)	(1,289)	(1,494)
Intercompany	0	0	0
Net cash used in investing activities	(53,810)	(10,625)	(113)
Cash flows from financing activities:
Change in restricted cash	0	0	0
Proceeds from issuance of debt	0	0	0
Payment of debt issuance costs	0	0	0
Repayment of senior notes		0	0
Payments on mortgages and land contracts due to land sellers and other loans	(36,918)	(66,296)	(26,298)
Proceeds from issuance of common stock, net	0	0
Issuance of common stock under employee stock plans	0	0	0
Payments of cash dividends	0	0	0
Stock repurchases	0	0	0
Intercompany	769,549	550,704	8,929
Net cash provided by financing activities	732,631	484,408	(17,369)
Net increase (decrease) in cash and cash equivalents	(1,828)	(9,580)	3,751
Cash and cash equivalents at beginning of year	39,952	49,532	45,781
Cash and cash equivalents at end of year	38,124	39,952	49,532
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	(32,671)	35,082	(3,049)
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	(248)	(5,023)	(392)
Proceeds from sale of investment in unconsolidated joint venture	10,110
Purchases of property and equipment, net	(626)	(583)	(80)
Intercompany	0	0	0
Net cash used in investing activities	9,236	(5,606)	(472)
Cash flows from financing activities:
Change in restricted cash	0	0	0
Proceeds from issuance of debt	0	0	0
Payment of debt issuance costs	0	0	0
Repayment of senior notes		0	0
Payments on mortgages and land contracts due to land sellers and other loans	0	0	0
Proceeds from issuance of common stock, net	0	0
Issuance of common stock under employee stock plans	0	0	0
Payments of cash dividends	0	0	0
Stock repurchases	0	0	0
Intercompany	25,075	(32,901)	(8,666)
Net cash provided by financing activities	25,075	(32,901)	(8,666)
Net increase (decrease) in cash and cash equivalents	1,640	(3,425)	(12,187)
Cash and cash equivalents at beginning of year	15,724	19,149	31,336
Cash and cash equivalents at end of year	17,364	15,724	19,149
Consolidating Adjustments
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	0	0	0
Cash flows from investing activities:
Return of investment in (contributions to) unconsolidated joint ventures	0	0	0
Proceeds from sale of investment in unconsolidated joint venture	0
Purchases of property and equipment, net	0	0	0
Intercompany	794,624	517,803	263
Net cash used in investing activities	794,624	517,803	263
Cash flows from financing activities:
Change in restricted cash	0	0	0
Proceeds from issuance of debt	0	0	0
Payment of debt issuance costs	0	0	0
Repayment of senior notes		0	0
Payments on mortgages and land contracts due to land sellers and other loans	0	0	0
Proceeds from issuance of common stock, net	0	0
Issuance of common stock under employee stock plans	0	0	0
Payments of cash dividends	0	0	0
Stock repurchases	0	0	0
Intercompany	(794,624)	(517,803)	(263)
Net cash provided by financing activities	(794,624)	(517,803)	(263)
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