Supplemental Guarantor Information (Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands		Feb. 29, 2020	Nov. 30, 2019	Feb. 28, 2019	Nov. 30, 2018
Assets
Cash and cash equivalents		$ 430,927	$ 454,858	$ 512,407	$ 575,119
Receivables		297,215	249,055
Inventories		3,728,616	3,704,602
Property and equipment, net		64,453	65,043
Other assets		129,719	83,041
Total assets		5,052,834	5,015,482
Liabilities and stockholders’ equity
Mortgages and notes payable		1,749,148	1,748,747
Intercompany payables		0	0
Stockholders’ equity		2,443,104	2,383,122	2,128,497	2,087,500
Total liabilities and stockholders’ equity		5,052,834	5,015,482
Reportable Legal Entities [Member] | KB Home Corporate [Member]
Assets
Cash and cash equivalents		309,983	357,966	415,471	429,977
Total assets		4,368,454	4,298,971
Liabilities and stockholders’ equity
Intercompany payables		71,346	60,964
Stockholders’ equity		2,443,104	2,383,122
Total liabilities and stockholders’ equity		4,368,454	4,298,971
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents		92,853	65,434	80,346	114,269
Total assets		3,984,806	3,981,908
Liabilities and stockholders’ equity
Intercompany payables		3,507,195	3,520,090
Stockholders’ equity		40,042	0
Total liabilities and stockholders’ equity		3,984,806	3,981,908
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents		28,091	31,458	16,590	30,873
Total assets		688,644	660,459
Liabilities and stockholders’ equity
Intercompany payables		248,424	229,049
Stockholders’ equity		122,063	115,753
Total liabilities and stockholders’ equity		688,644	660,459
Consolidating Adjustments [Member]
Assets
Cash and cash equivalents		0	0	0	$ 0
Total assets		(3,989,070)	(3,925,856)
Liabilities and stockholders’ equity
Intercompany payables		(3,826,965)	(3,810,103)
Stockholders’ equity		(162,105)	(115,753)
Total liabilities and stockholders’ equity		(3,989,070)	(3,925,856)
Home Building [Member]
Assets
Cash and cash equivalents		429,706	453,814	511,690
Receivables		297,215	249,055
Inventories		3,728,616	3,704,602
Investments in unconsolidated joint ventures		57,147	57,038
Property and equipment, net		64,453	65,043
Deferred tax assets, net		312,166	364,493
Other assets		129,719	83,041
Intercompany receivables		0	0
Investments in subsidiaries		0	0
Total assets		5,019,022	4,977,086
Liabilities and stockholders’ equity
Accounts payable and accrued expenses		858,539	881,555
Mortgages and notes payable		1,749,148	1,748,747
Total Liabilities		2,607,687	2,630,302
Home Building [Member] | Reportable Legal Entities [Member] | KB Home Corporate [Member]
Assets
Cash and cash equivalents		309,983	357,966
Receivables		44,583	1,934
Inventories		0	0
Investments in unconsolidated joint ventures		0	0
Property and equipment, net		25,185	24,250
Deferred tax assets, net		93,510	96,301
Other assets		102,826	78,686
Intercompany receivables		3,630,262	3,624,081
Investments in subsidiaries		162,105	115,753
Total assets		576,087	559,137
Liabilities and stockholders’ equity
Accounts payable and accrued expenses		137,855	139,137
Mortgages and notes payable		1,716,149	1,715,748
Total Liabilities		1,854,004	1,854,885
Home Building [Member] | Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents		92,853	65,434
Receivables		184,288	181,047
Inventories		3,391,612	3,400,307
Investments in unconsolidated joint ventures		57,147	57,038
Property and equipment, net		36,047	37,539
Deferred tax assets, net		203,661	237,877
Other assets		19,198	2,666
Intercompany receivables		0	0
Investments in subsidiaries		0	0
Total assets		3,984,806	3,981,908
Liabilities and stockholders’ equity
Accounts payable and accrued expenses		429,680	453,929
Mortgages and notes payable		7,889	7,889
Total Liabilities		437,569	461,818
Home Building [Member] | Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents		26,870	30,414
Receivables		68,344	66,074
Inventories		337,004	304,295
Investments in unconsolidated joint ventures		0	0
Property and equipment, net		3,221	3,254
Deferred tax assets, net		14,995	30,315
Other assets		7,695	1,689
Intercompany receivables		196,703	186,022
Investments in subsidiaries		0	0
Total assets		458,129	436,041
Liabilities and stockholders’ equity
Accounts payable and accrued expenses		291,004	288,489
Mortgages and notes payable		25,110	25,110
Total Liabilities		316,114	313,599
Home Building [Member] | Consolidating Adjustments [Member]
Assets
Cash and cash equivalents		0	0
Receivables		0	0
Inventories		0	0
Investments in unconsolidated joint ventures		0	0
Property and equipment, net		0	0
Deferred tax assets, net		0	0
Other assets		0	0
Intercompany receivables		(3,826,965)	(3,810,103)
Investments in subsidiaries		(162,105)	(115,753)
Total assets		0	0
Liabilities and stockholders’ equity
Accounts payable and accrued expenses		0	0
Mortgages and notes payable		0	0
Total Liabilities		0	0
Financial Service [Member]
Assets
Cash and cash equivalents		1,221	1,044	$ 717
Receivables		1,589	2,232
Investments in unconsolidated joint ventures		9,446	14,374
Other assets	[1]	21,556	20,746
Total assets		33,812	38,396
Liabilities and stockholders’ equity
Accounts payable and accrued expenses		2,043	2,058
Financial services		2,043	2,058
Financial Service [Member] | Reportable Legal Entities [Member] | KB Home Corporate [Member]
Assets
Total assets		0	0
Liabilities and stockholders’ equity
Financial services		0	0
Financial Service [Member] | Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Total assets		0	0
Liabilities and stockholders’ equity
Financial services		0	0
Financial Service [Member] | Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Total assets		33,812	38,396
Liabilities and stockholders’ equity
Financial services		2,043	2,058
Financial Service [Member] | Consolidating Adjustments [Member]
Assets
Total assets		0	0
Liabilities and stockholders’ equity
Financial services		$ 0	$ 0

[1] Other assets at February 29, 2020 and November 30, 2019 included $21.1 million and $20.6 million, respectively, of contract assets for estimated future renewal commissions related to then-existing insurance policies.