Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 29, 2016	Feb. 28, 2015
Cash flows from operating activities:
Net cash used in operating activities	$ (143,313)	$ (48,909)
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	(291)	(2,414)
Purchases of property and equipment, net	(1,413)	(586)
Intercompany	0	0
Net cash used in investing activities	(1,704)	(3,000)
Cash flows from financing activities:
Change in restricted cash	4,987	(749)
Proceeds from issuance of debt	0	250,000
Payment of debt issuance costs	0	(2,989)
Payments on mortgages and land contracts due to land sellers and other loans	(5,659)	(2,722)
Payments of cash dividends	(2,270)	(2,299)
Stock repurchases	(87,526)	(21)
Intercompany	0	0
Net cash provided by (used in) financing activities	(90,468)	241,220
Net increase (decrease) in cash and cash equivalents	(235,485)	189,311
Cash and cash equivalents at beginning of period	560,341	358,768
Cash and cash equivalents at end of period	324,856	548,079
KB Home Corporate
Cash flows from operating activities:
Net cash used in operating activities	13,908	5,369
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	0	0
Purchases of property and equipment, net	(1,129)	(37)
Intercompany	(115,459)	(80,424)
Net cash used in investing activities	(116,588)	(80,461)
Cash flows from financing activities:
Change in restricted cash	4,987	(749)
Proceeds from issuance of debt		250,000
Payment of debt issuance costs		(2,989)
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Payments of cash dividends	(2,270)	(2,299)
Stock repurchases	(87,526)	(21)
Intercompany	0	0
Net cash provided by (used in) financing activities	(84,809)	243,942
Net increase (decrease) in cash and cash equivalents	(187,489)	168,850
Cash and cash equivalents at beginning of period	444,850	303,280
Cash and cash equivalents at end of period	257,361	472,130
Guarantor Subsidiaries
Cash flows from operating activities:
Net cash used in operating activities	(141,026)	(27,884)
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	(291)	(2,414)
Purchases of property and equipment, net	(265)	(528)
Intercompany	0	0
Net cash used in investing activities	(556)	(2,942)
Cash flows from financing activities:
Change in restricted cash	0	0
Proceeds from issuance of debt		0
Payment of debt issuance costs		0
Payments on mortgages and land contracts due to land sellers and other loans	(5,659)	(2,722)
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	107,758	59,593
Net cash provided by (used in) financing activities	102,099	56,871
Net increase (decrease) in cash and cash equivalents	(39,483)	26,045
Cash and cash equivalents at beginning of period	98,281	37,112
Cash and cash equivalents at end of period	58,798	63,157
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net cash used in operating activities	(16,195)	(26,394)
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	0	0
Purchases of property and equipment, net	(19)	(21)
Intercompany	0	0
Net cash used in investing activities	(19)	(21)
Cash flows from financing activities:
Change in restricted cash	0	0
Proceeds from issuance of debt		0
Payment of debt issuance costs		0
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	7,701	20,831
Net cash provided by (used in) financing activities	7,701	20,831
Net increase (decrease) in cash and cash equivalents	(8,513)	(5,584)
Cash and cash equivalents at beginning of period	17,210	18,376
Cash and cash equivalents at end of period	8,697	12,792
Consolidating Adjustments
Cash flows from operating activities:
Net cash used in operating activities	0	0
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	0	0
Purchases of property and equipment, net	0	0
Intercompany	115,459	80,424
Net cash used in investing activities	115,459	80,424
Cash flows from financing activities:
Change in restricted cash	0	0
Proceeds from issuance of debt		0
Payment of debt issuance costs		0
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	(115,459)	(80,424)
Net cash provided by (used in) financing activities	(115,459)	(80,424)
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