Supplemental Guarantor Information (Condensed Consolidating Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2014	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2011
Assets
Cash and cash equivalents	$ 358,768	$ 532,523	$ 525,688	$ 418,074
Restricted cash	27,235	41,906
Receivables	125,488	75,749
Inventory, Operative Builders	3,218,387	2,298,577
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	79,441	130,192
Deferred tax assets, net	825,232	0
Other assets	114,915	107,076
Investments in subsidiaries	0	0
Total assets	4,757,550	3,193,635
Due from Affiliates	0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	582,598	504,458
Notes payable	2,576,525	2,150,498
Financial services	2,517	2,593
Due to Affiliate	0	0
Stockholder's equity	1,595,910	536,086	376,806	442,657
Total liabilities and Stockholders' equity	4,757,550	3,193,635
KB Home Corporate
Assets
Cash and cash equivalents	303,280	476,847	457,007	340,957
Restricted cash	27,235	41,906
Receivables	15	1,472
Inventory, Operative Builders	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	215,923
Other assets	99,099	97,647
Investments in subsidiaries	39,356	39,955
Total assets	4,267,520	2,787,556
Due from Affiliates	3,582,612	2,129,729
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	138,298	117,875
Notes payable	2,513,165	2,111,773
Financial services	0	0
Due to Affiliate	20,147	21,822
Stockholder's equity	1,595,910	536,086
Total liabilities and Stockholders' equity	4,267,520	2,787,556
Guarantor Subsidiaries
Assets
Cash and cash equivalents	38,124	39,952	49,532	45,781
Restricted cash	0	0
Receivables	123,024	73,668
Inventory, Operative Builders	2,980,056	2,084,177
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	79,441	123,623
Deferred tax assets, net	552,653
Other assets	13,922	8,393
Investments in subsidiaries	0	0
Total assets	3,787,220	2,329,813
Due from Affiliates	0	0
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	331,361	268,431
Notes payable	63,360	38,725
Financial services	0	0
Due to Affiliate	3,392,499	2,022,657
Stockholder's equity	0	0
Total liabilities and Stockholders' equity	3,787,220	2,329,813
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	17,364	15,724	19,149	31,336
Restricted cash	0	0
Receivables	2,449	609
Inventory, Operative Builders	238,331	214,400
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	6,569
Deferred tax assets, net	56,656
Other assets	1,894	1,036
Investments in subsidiaries	0	0
Total assets	437,697	363,779
Due from Affiliates	112,919	117,829
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	112,939	118,152
Notes payable	0	0
Financial services	2,517	2,593
Due to Affiliate	282,885	203,079
Stockholder's equity	39,356	39,955
Total liabilities and Stockholders' equity	437,697	363,779
Consolidating Adjustments
Assets
Cash and cash equivalents	0	0	0	0
Restricted cash	0	0
Receivables	0	0
Inventory, Operative Builders	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Deferred tax assets, net	0
Other assets	0	0
Investments in subsidiaries	(39,356)	(39,955)
Total assets	(3,734,887)	(2,287,513)
Due from Affiliates	(3,695,531)	(2,247,558)
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	0	0
Notes payable	0	0
Financial services	0	0
Due to Affiliate	(3,695,531)	(2,247,558)
Stockholder's equity	(39,356)	(39,955)
Total liabilities and Stockholders' equity	(3,734,887)	(2,287,513)
Homebuilding [Member]
Assets
Cash and cash equivalents	356,366	530,095	524,765
Total assets	4,747,064	3,183,595
Liabilities and stockholders' equity
Total Homebuilding	3,159,123	2,654,956
Homebuilding [Member] | KB Home Corporate
Assets
Cash and cash equivalents	303,280	476,847
Total assets	645,552	617,872
Liabilities and stockholders' equity
Total Homebuilding	2,651,463	2,229,648
Homebuilding [Member] | Guarantor Subsidiaries
Assets
Cash and cash equivalents	38,124	39,952
Total assets	3,787,220	2,329,813
Liabilities and stockholders' equity
Total Homebuilding	394,721	307,156
Homebuilding [Member] | Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	14,962	13,296
Total assets	314,292	235,910
Liabilities and stockholders' equity
Total Homebuilding	112,939	118,152
Homebuilding [Member] | Consolidating Adjustments
Assets
Cash and cash equivalents	0	0
Total assets	0	0
Liabilities and stockholders' equity
Total Homebuilding	0	0
Financial services [Member]
Assets
Cash and cash equivalents	2,402	2,428	923
Receivables	1,738	2,084
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	6,149	5,490
Other assets	197	38
Total assets	10,486	10,040
Liabilities and stockholders' equity
Accounts payable, accrued expenses and other liabilities	2,517	2,593
Financial services [Member] | KB Home Corporate
Assets
Total assets	0	0
Financial services [Member] | Guarantor Subsidiaries
Assets
Total assets	0	0
Financial services [Member] | Non-Guarantor Subsidiaries
Assets
Total assets	10,486	10,040
Financial services [Member] | Consolidating Adjustments
Assets
Total assets	$ 0	$ 0