Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2013
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	$ 181,185	$ (630,691)	$ (443,486)
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	(20,626)	(49,097)	(14,359)
Return of investments in unconsolidated joint ventures	14,000	0	0
Proceeds from sale of investment in unconsolidated joint venture	0	10,110	0
Purchases of property and equipment, net	(4,677)	(5,795)	(2,391)
Intercompany	0	0	0
Net cash used in investing activities	(11,303)	(44,782)	(16,750)
Cash flows from financing activities:
Change in restricted cash	17,891	14,671	456
Proceeds from issuance of debt	250,000	400,000	680,000
Payment of debt issuance costs	(4,561)	(5,448)	(16,525)
Repayment of senior notes	(199,906)	0	(225,394)
Payments on mortgages and land contracts due to land sellers and other loans	(22,877)	(36,918)	(66,296)
Proceeds from issuance of common stock, net	0	137,045	109,503
Issuance of common stock under employee stock plans	740	1,896	2,181
Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities	157	0	0
Payments of cash dividends	(9,186)	(8,982)	(8,366)
Stock repurchases	(567)	(546)	(8,488)
Intercompany	0	0	0
Net cash provided by financing activities	31,691	501,718	467,071
Net increase (decrease) in cash and cash equivalents	201,573	(173,755)	6,835
Cash and cash equivalents at beginning of year	358,768	532,523	525,688
Cash and cash equivalents at end of year	560,341	358,768	532,523
KB Home Corporate
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	44,422	82,629	4,795
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	0	0	0
Return of investments in unconsolidated joint ventures	0
Proceeds from sale of investment in unconsolidated joint venture		0
Purchases of property and equipment, net	(2,890)	(208)	(519)
Intercompany	45,470	(794,624)	(517,803)
Net cash used in investing activities	42,580	(794,832)	(518,322)
Cash flows from financing activities:
Change in restricted cash	17,891	14,671	456
Proceeds from issuance of debt	250,000	400,000	680,000
Payment of debt issuance costs	(4,561)	(5,448)	(16,525)
Repayment of senior notes	(199,906)		(225,394)
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	740	1,896	2,181
Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities	157
Payments of cash dividends	(9,186)	(8,982)	(8,366)
Stock repurchases	(567)	(546)	(8,488)
Intercompany	0	0	0
Net cash provided by financing activities	54,568	538,636	533,367
Net increase (decrease) in cash and cash equivalents	141,570	(173,567)	19,840
Cash and cash equivalents at beginning of year	303,280	476,847	457,007
Cash and cash equivalents at end of year	444,850	303,280	476,847
Guarantor Subsidiaries
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	125,068	(643,702)	(457,390)
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	(20,625)	(48,846)	(9,334)
Return of investments in unconsolidated joint ventures	14,000
Proceeds from sale of investment in unconsolidated joint venture		0
Purchases of property and equipment, net	(1,704)	(4,412)	(1,254)
Intercompany	0	0	0
Net cash used in investing activities	(8,329)	(53,258)	(10,588)
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	(22,877)	(36,918)	(66,296)
Proceeds from issuance of common stock, net		0	0
Issuance of common stock under employee stock plans	0	0	0
Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities	0
Payments of cash dividends	0	0	0
Stock repurchases	0	0	0
Intercompany	(32,693)	733,033	523,013
Net cash provided by financing activities	(55,570)	696,115	456,717
Net increase (decrease) in cash and cash equivalents	61,169	(845)	(11,261)
Cash and cash equivalents at beginning of year	37,112	37,957	49,218
Cash and cash equivalents at end of year	98,281	37,112	37,957
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	11,695	(69,618)	9,109
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	(1)	(251)	(5,025)
Return of investments in unconsolidated joint ventures	0
Proceeds from sale of investment in unconsolidated joint venture		10,110
Purchases of property and equipment, net	(83)	(1,175)	(618)
Intercompany	0	0	0
Net cash used in investing activities	(84)	8,684	(5,643)
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
Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities	0
Payments of cash dividends	0	0	0
Stock repurchases	0	0	0
Intercompany	(12,777)	61,591	(5,210)
Net cash provided by financing activities	(12,777)	61,591	(5,210)
Net increase (decrease) in cash and cash equivalents	(1,166)	657	(1,744)
Cash and cash equivalents at beginning of year	18,376	17,719	19,463
Cash and cash equivalents at end of year	17,210	18,376	17,719
Consolidating Adjustments
Condensed Consolidated Statements of Cash Flows
Net cash provided by (used in) operating activities	0	0	0
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	0	0	0
Return of investments in unconsolidated joint ventures	0
Proceeds from sale of investment in unconsolidated joint venture		0
Purchases of property and equipment, net	0	0	0
Intercompany	(45,470)	794,624	517,803
Net cash used in investing activities	(45,470)	794,624	517,803
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
Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities	0
Payments of cash dividends	0	0	0
Stock repurchases	0	0	0
Intercompany	45,470	(794,624)	(517,803)
Net cash provided by financing activities	45,470	(794,624)	(517,803)
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