Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) - USD ($) $ in Thousands	6 Months Ended
	May 31, 2016	May 31, 2015
Cash flows from operating activities:
Net cash used in operating activities	$ (167,459)	$ (135,900)
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	(750)	(13,244)
Purchases of property and equipment, net	(2,876)	(1,590)
Intercompany	0	0
Net cash used in investing activities	(3,626)	(14,834)
Cash flows from financing activities:
Change in restricted cash	(5,827)	(22)
Proceeds from issuance of debt	0	250,000
Payment of debt issuance costs	0	(3,337)
Payments on mortgages and land contracts due to land sellers and other loans	(26,639)	(7,757)
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options	0	25
Payments of cash dividends	(4,364)	(4,599)
Stock repurchases	(87,531)	(300)
Intercompany	0	0
Net cash provided by (used in) financing activities	(112,707)	234,054
Net increase (decrease) in cash and cash equivalents	(283,792)	83,320
Cash and cash equivalents at beginning of period	560,341	358,768
Cash and cash equivalents at end of period	276,549	442,088
KB Home Corporate
Cash flows from operating activities:
Net cash used in operating activities	6,508	17,630
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	0	0
Purchases of property and equipment, net	(2,437)	(399)
Intercompany	(167,470)	(187,947)
Net cash used in investing activities	(169,907)	(188,346)
Cash flows from financing activities:
Change in restricted cash	(5,827)	(22)
Proceeds from issuance of debt		250,000
Payment of debt issuance costs		(3,337)
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options		25
Payments of cash dividends	(4,364)	(4,599)
Stock repurchases	(87,531)	(300)
Intercompany	0	0
Net cash provided by (used in) financing activities	(86,068)	241,811
Net increase (decrease) in cash and cash equivalents	(249,467)	71,095
Cash and cash equivalents at beginning of period	444,850	303,280
Cash and cash equivalents at end of period	195,383	374,375
Guarantor Subsidiaries
Cash flows from operating activities:
Net cash used in operating activities	(179,676)	(119,782)
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	(750)	(13,244)
Purchases of property and equipment, net	(331)	(1,135)
Intercompany	0	0
Net cash used in investing activities	(1,081)	(14,379)
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	(26,639)	(7,757)
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options		0
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	173,763	160,114
Net cash provided by (used in) financing activities	147,124	152,357
Net increase (decrease) in cash and cash equivalents	(33,633)	18,196
Cash and cash equivalents at beginning of period	98,281	37,112
Cash and cash equivalents at end of period	64,648	55,308
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net cash used in operating activities	5,709	(33,748)
Cash flows from investing activities:
Contributions to unconsolidated joint ventures	0	0
Purchases of property and equipment, net	(108)	(56)
Intercompany	0	0
Net cash used in investing activities	(108)	(56)
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
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options		0
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	(6,293)	27,833
Net cash provided by (used in) financing activities	(6,293)	27,833
Net increase (decrease) in cash and cash equivalents	(692)	(5,971)
Cash and cash equivalents at beginning of period	17,210	18,376
Cash and cash equivalents at end of period	16,518	12,405
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	167,470	187,947
Net cash used in investing activities	167,470	187,947
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
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options		0
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	(167,470)	(187,947)
Net cash provided by (used in) financing activities	(167,470)	(187,947)
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