Supplemental Guarantor Information (Condensed Consolidated Statements of Cash Flows) (Details) - USD ($) $ in Thousands	6 Months Ended
	May. 31, 2015	May. 31, 2014
Cash flows from operating activities:
Net cash used in operating activities	$ (135,900)	$ (554,529)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(13,244)	(16,242)
Proceeds from sale of investment in unconsolidated joint venture	0	10,110
Purchases of property and equipment, net	(1,590)	(3,012)
Intercompany	0	0
Net cash provided by (used in) investing activities	(14,834)	(9,144)
Cash flows from financing activities:
Change in restricted cash	22	(2,331)
Proceeds from issuance of debt	250,000	400,000
Payment of debt issuance costs	(3,337)	(5,448)
Payments on mortgages and land contracts due to land sellers and other loans	(7,757)	(6,476)
Proceeds from Issuance or Sale of Equity	0	137,045
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options	25	64
Payments of cash dividends	(4,599)	(4,388)
Stock repurchases	(300)	(46)
Intercompany	0	0
Net cash provided by (used in) financing activities	234,054	518,420
Net increase (decrease) in cash and cash equivalents	83,320	(45,253)
Cash and cash equivalents at beginning of period	358,768	532,523
Cash and cash equivalents at end of period	442,088	487,270
KB Home Corporate
Cash flows from operating activities:
Net cash used in operating activities	17,630	46,425
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	0	0
Proceeds from sale of investment in unconsolidated joint venture		0
Purchases of property and equipment, net	(399)	(84)
Intercompany	(187,947)	(635,273)
Net cash provided by (used in) investing activities	(188,346)	(635,357)
Cash flows from financing activities:
Change in restricted cash	22	(2,331)
Proceeds from issuance of debt	250,000	400,000
Payment of debt issuance costs	(3,337)	(5,448)
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Proceeds from Issuance or Sale of Equity		137,045
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options	25	64
Payments of cash dividends	(4,599)	(4,388)
Stock repurchases	(300)	(46)
Intercompany	0	0
Net cash provided by (used in) financing activities	241,811	524,896
Net increase (decrease) in cash and cash equivalents	71,095	(64,036)
Cash and cash equivalents at beginning of period	303,280	476,847
Cash and cash equivalents at end of period	374,375	412,811
Guarantor Subsidiaries
Cash flows from operating activities:
Net cash used in operating activities	(117,666)	(549,367)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(13,242)	(15,994)
Proceeds from sale of investment in unconsolidated joint venture		0
Purchases of property and equipment, net	(1,165)	(2,539)
Intercompany	0	0
Net cash provided by (used in) investing activities	(14,407)	(18,533)
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
Payments on mortgages and land contracts due to land sellers and other loans	(7,757)	(6,476)
Proceeds from Issuance or Sale of Equity		0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options	0	0
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	161,116	598,451
Net cash provided by (used in) financing activities	153,359	591,975
Net increase (decrease) in cash and cash equivalents	21,286	24,075
Cash and cash equivalents at beginning of period	38,124	39,952
Cash and cash equivalents at end of period	59,410	64,027
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net cash used in operating activities	(35,864)	(51,587)
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	(2)	(248)
Proceeds from sale of investment in unconsolidated joint venture		10,110
Purchases of property and equipment, net	(26)	(389)
Intercompany	0	0
Net cash provided by (used in) investing activities	(28)	9,473
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
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Proceeds from Issuance or Sale of Equity		0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options	0	0
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	26,831	36,822
Net cash provided by (used in) financing activities	26,831	36,822
Net increase (decrease) in cash and cash equivalents	(9,061)	(5,292)
Cash and cash equivalents at beginning of period	17,364	15,724
Cash and cash equivalents at end of period	8,303	10,432
Consolidating Adjustments
Cash flows from operating activities:
Net cash used in operating activities	0	0
Cash flows from investing activities:
Return of investments in (contributions to) unconsolidated joint ventures	0	0
Proceeds from sale of investment in unconsolidated joint venture		0
Purchases of property and equipment, net	0	0
Intercompany	187,947	635,273
Net cash provided by (used in) investing activities	187,947	635,273
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
Payments on mortgages and land contracts due to land sellers and other loans	0	0
Proceeds from Issuance or Sale of Equity		0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options	0	0
Payments of cash dividends	0	0
Stock repurchases	0	0
Intercompany	(187,947)	(635,273)
Net cash provided by (used in) financing activities	(187,947)	(635,273)
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