Supplemental Guarantor Information (Condensed Consolidating Statements of Operations) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Nov. 30, 2015	Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2013
Condensed Consolidated Statements of Operations
Revenues		$ 985,783	$ 843,157	$ 622,969	$ 580,121	$ 796,041	$ 589,214	$ 565,007	$ 450,687	$ 3,032,030	$ 2,400,949	$ 2,097,130
Homebuilding:
Revenues										3,020,987	2,389,643	2,084,978
Construction and land costs										(2,539,368)	(1,985,651)	(1,737,086)
Selling, general and administrative expenses										(342,998)	(288,023)	(255,808)
Operating income (loss)										138,621	115,969	92,084
Interest income										458	443	792
Interest Expense	[1]									(21,856)	(30,750)	(62,690)
Intercompany Interest Income (Expense)										0	0	0
Equity in income (loss) of unconsolidated joint ventures										2,488	1,427	(933)
Pretax income (loss)		69,917	33,954	12,673	10,499	28,601	28,661	26,924	10,763	127,043	94,949	38,363
Income tax benefit						824,200				(42,400)	823,400	1,600
Income (Loss) from Subsidiaries, Net of Tax										0	0	0
Net income (loss)		$ 44,017	$ 23,254	$ 9,573	$ 7,799	$ 852,801	$ 28,361	$ 26,624	$ 10,563	84,643	918,349	39,963
KB Home Corporate
Condensed Consolidated Statements of Operations
Revenues										0	0	0
Homebuilding:
Revenues										0	0	0
Construction and land costs										0	0	0
Selling, general and administrative expenses										(86,053)	(68,717)	(60,545)
Operating income (loss)										(86,053)	(68,717)	(60,545)
Interest income										451	432	768
Interest Expense										(180,701)	(165,485)	(143,902)
Intercompany Interest Income (Expense)										289,727	287,017	203,096
Equity in income (loss) of unconsolidated joint ventures										0	0
Pretax income (loss)										23,424	53,247	(583)
Income tax benefit										2,000	215,691	100
Income (Loss) from Subsidiaries, Net of Tax										59,219	649,411	40,446
Net income (loss)										84,643	918,349	39,963
Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues										2,653,372	2,031,564	1,792,040
Homebuilding:
Revenues										2,653,372	2,031,564	1,792,040
Construction and land costs										(2,209,472)	(1,673,916)	(1,480,822)
Selling, general and administrative expenses										(213,292)	(176,795)	(151,923)
Operating income (loss)										230,608	180,853	159,295
Interest income										6	9	18
Interest Expense										(6,184)	(6,056)	(5,199)
Intercompany Interest Income (Expense)										(109,208)	(127,191)	(102,172)
Equity in income (loss) of unconsolidated joint ventures										(1,803)	(2,549)
Pretax income (loss)										113,419	45,066	49,439
Income tax benefit										(42,700)	551,203	1,800
Income (Loss) from Subsidiaries, Net of Tax										0	0	0
Net income (loss)										70,719	596,269	51,239
Non-Guarantor Subsidiaries
Condensed Consolidated Statements of Operations
Revenues										378,658	369,385	305,090
Homebuilding:
Revenues										367,615	358,079	292,938
Construction and land costs										(329,896)	(311,735)	(256,264)
Selling, general and administrative expenses										(43,653)	(42,511)	(43,340)
Operating income (loss)										(5,934)	3,833	(6,666)
Interest income										1	2	6
Interest Expense										0	0	0
Intercompany Interest Income (Expense)										(15,490)	(19,035)	(14,513)
Equity in income (loss) of unconsolidated joint ventures										(1)	3,290
Pretax income (loss)										(9,800)	(3,364)	(10,493)
Income tax benefit										(1,700)	56,506	(300)
Income (Loss) from Subsidiaries, Net of Tax										0	0	0
Net income (loss)										(11,500)	53,142	(10,793)
Consolidating Adjustments
Condensed Consolidated Statements of Operations
Revenues										0	0	0
Homebuilding:
Revenues										0	0	0
Construction and land costs										0	0	0
Selling, general and administrative expenses										0	0	0
Operating income (loss)										0	0	0
Interest income										0	0	0
Interest Expense										165,029	140,791	86,411
Intercompany Interest Income (Expense)										(165,029)	(140,791)	(86,411)
Equity in income (loss) of unconsolidated joint ventures										0	0
Pretax income (loss)										0	0	0
Income tax benefit										0	0	0
Income (Loss) from Subsidiaries, Net of Tax										(59,219)	(649,411)	(40,446)
Net income (loss)										(59,219)	(649,411)	(40,446)
Homebuilding [Member]
Condensed Consolidated Statements of Operations
Revenues										3,020,987	2,389,643	2,084,978
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures										(1,804)	741	(2,007)
Pretax income (loss)										115,419	86,403	28,179
Homebuilding [Member] | KB Home Corporate
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures												0
Pretax income (loss)										23,424	53,247	(583)
Homebuilding [Member] | Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures												(2,503)
Pretax income (loss)										113,419	45,066	49,439
Homebuilding [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures												496
Pretax income (loss)										(21,424)	(11,910)	(20,677)
Homebuilding [Member] | Consolidating Adjustments
Homebuilding:
Equity in income (loss) of unconsolidated joint ventures												0
Pretax income (loss)										0	0	0
Financial services [Member]
Condensed Consolidated Statements of Operations
Revenues										11,043	11,306	12,152
Homebuilding:
Operating income (loss)										7,332	7,860	9,110
Equity in income (loss) of unconsolidated joint ventures										4,292	686	1,074
Pretax income (loss)										11,624	8,546	10,184
Financial services [Member] | KB Home Corporate
Homebuilding:
Pretax income (loss)										0	0	0
Financial services [Member] | Guarantor Subsidiaries
Homebuilding:
Pretax income (loss)										0	0	0
Financial services [Member] | Non-Guarantor Subsidiaries
Homebuilding:
Pretax income (loss)										11,624	8,546	10,184
Financial services [Member] | Consolidating Adjustments
Homebuilding:
Pretax income (loss)										$ 0	$ 0	$ 0

[1] Amounts for the year ended November 30, 2013 included losses on the early extinguishment of debt of $10.4 million associated with the purchase and retirement of certain senior notes ahead of their maturity.