Inventories (Details) - USD ($) $ in Thousands	12 Months Ended
Nov. 30, 2020	Nov. 30, 2019
Inventories
Homes under construction	$ 1,437,911	$ 1,340,412
Land under development	2,459,571	2,364,190
Total	3,897,482	3,704,602
Land held for future development or sale	74,000	131,200
Land held for future development	$ 1,300	$ 19,300
Real estate held for sale duration	1 year

Real Estate Held for Sale Duration

No definition available.

Name:	kbh_RealEstateHeldforSaleDuration
Namespace Prefix:	kbh_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of capitalized construction costs of homes for future sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_InventoryHomesUnderConstruction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount net of impairment reserves as of the balance sheet date primarily consisting of deposits for land purchases (including option payments), related acquisition costs, and land which is not expected to be developed in the next two years.

+ References

+ Details

Name:	us-gaap_InventoryLandHeldForDevelopmentAndSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of parcels of land held for sale, and on which the entity has no intention or no further intention to perform construction activities.

+ References

+ Details

Name:	us-gaap_InventoryLandHeldForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The net carrying amount as of the balance sheet date of the sum of the various components of an operative builder's inventory, including finished homes. Operative builders primarily consist of entities that develop land, construct residential homes and commercial and industrial buildings thereon, and sell them to home buyers and operators of the commercial and industrial properties.

+ References

+ Details

Name:	us-gaap_InventoryOperativeBuilders
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_InventoryOperativeBuildersAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date, net of valuation allowances and impairment losses, of costs of land expected to be developed in the near term plus capitalized costs of development, for purposes of selling completed units to home buyers or commercial or industrial entities..

+ References

+ Details

Name:	us-gaap_InventoryRealEstateLandAndLandDevelopmentCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant