Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Nov. 30, 2015
Segment Reporting Information [Line Items]
Operations	Operations. KB Home is a builder of attached and detached single-family residential homes, townhomes and condominiums. As of November 30, 2015, we conducted ongoing operations in Arizona, California, Colorado, Florida, Maryland, Nevada, North Carolina, Texas and Virginia. We also offer property and casualty insurance and, in certain instances, earthquake, flood and personal property insurance to our homebuyers in the same markets where we build homes, and provide title services in the majority of our markets located within our Central and Southeast homebuilding reporting segments. Since July 2014, we have also offered mortgage banking services, including mortgage loan originations, to our homebuyers indirectly through HCM, a joint venture of a subsidiary of ours and a subsidiary of Nationstar. HCM is accounted for as an unconsolidated joint venture within our financial services reporting segment.
Basis of Presentation	Basis of Presentation. Our consolidated financial statements have been prepared in accordance with GAAP and include our accounts and those of the consolidated subsidiaries in which we have a controlling financial interest. All intercompany balances and transactions have been eliminated in consolidation. Investments in unconsolidated joint ventures in which we have less than a controlling financial interest are accounted for using the equity method.
Use of Estimates	Use of Estimates. The preparation of financial statements in conformity with GAAP requires management to make informed estimates and judgments that affect the amounts reported in our consolidated financial statements and accompanying notes. Actual results could differ from those estimates.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents and Restricted Cash. We consider all highly liquid short-term investments purchased with an original maturity of three months or less to be cash equivalents.
Property and Equipment and Depreciation	Property and Equipment and Depreciation. Property and equipment are recorded at cost and are depreciated over their estimated useful lives, which generally range from two to 10 years, using the straight-line method. Repair and maintenance costs are expensed as incurred.
Homebuilding Operations	Homebuilding Operations. Revenues from housing and other real estate sales are recognized when sales are closed and title passes to the buyer. Sales are closed when all of the following conditions are met: a sale is consummated, a sufficient down payment is received, the earnings process is complete and the collection of any remaining receivables is reasonably assured. Concurrent with the recognition of revenues in our consolidated statements of operations, sales incentives in the form of price concessions on the selling price of a home are recorded as a reduction of revenues, while the cost of sales incentives in the form of free products or services to homebuyers, including option upgrades and closing cost allowances used to cover a portion of the fees and costs charged to a homebuyer, is reflected as construction and land costs. Construction and land costs are comprised of direct and allocated costs, including estimated future costs for the limited warranty we provide on our homes and certain amenities within a community. Land acquisition, land development and other common costs are generally allocated on a relative fair value basis to the homes or lots within the applicable community or land parcel. Land acquisition and land development costs include related interest and real estate taxes. Housing and land inventories are stated at cost, unless the carrying value is determined not to be recoverable, in which case the affected inventories are written down to fair value or fair value less costs to sell. Real estate assets, such as our housing and land inventories, are tested for recoverability whenever events or changes in circumstances indicate that their carrying value may not be recoverable. Recoverability is measured by comparing the carrying value of an asset to the undiscounted future net cash flows expected to be generated by the asset. These impairment evaluations are significantly impacted by estimates for the amounts and timing of future revenues, costs and expenses, and other factors. If the carrying value of real estate assets is determined not to be recoverable, the impairment charge to be recognized is measured by the amount by which the carrying value of the affected asset exceeds its estimated fair value. For land held for sale, if the fair value less costs to sell exceeds the asset’s carrying value, no impairment charge is recognized.
Capitalized Interest	Capitalized Interest. Interest is capitalized to inventories while the related communities are being actively developed and until homes are completed. Capitalized interest is amortized to construction and land costs as the related inventories are delivered to homebuyers or land buyers (as applicable). For land held for future development, applicable interest is expensed as incurred.
Fair Value Measurements	Fair Value Measurements. Fair value measurements are used for inventories on a nonrecurring basis when events and circumstances indicate that their carrying value is not recoverable. Fair value is determined based on estimated future net cash flows discounted for inherent risks associated with the real estate assets, or other valuation techniques. Our financial instruments consist of cash and cash equivalents, restricted cash, senior notes, convertible senior notes, and mortgages and land contracts due to land sellers and other loans. Fair value measurements of financial instruments are determined by various market data and other valuation techniques as appropriate. When available, we use quoted market prices in active markets to determine fair value.
Warranty Costs	Warranty Costs. We provide a limited warranty on all of our homes. We estimate the costs that may be incurred under each limited warranty and record a liability in the amount of such costs at the time the revenue associated with the sale of each home is recognized. Our primary assumption in estimating the amounts we accrue for warranty costs is that historical claims experience is a strong indicator of future claims experience. Factors that affect our warranty liability include the number of homes delivered, historical and anticipated rates of warranty claims, and cost per claim. We periodically assess the adequacy of our accrued warranty liability and adjust the amount as necessary based on our assessment.
Self-Insurance	Self-Insurance. We self-insure a portion of our overall risk through the use of a captive insurance subsidiary. We also maintain certain other insurance policies. We record expenses and liabilities based on the estimated costs required to cover our self-insured retention and deductible amounts under our insurance policies, and the estimated costs of potential claims and claim adjustment expenses that are above our coverage limits or that are not covered by our insurance policies. These estimated costs are based on an analysis of our historical claims and industry data, and include an estimate of construction defect claims incurred but not yet reported. We engage a third-party actuary that uses our historical claim and expense data, as well as industry data, to estimate our liabilities related to unpaid claims, claim adjustment expenses, third-party recoveries and incurred but not yet reported claims associated with the risks that we are assuming with respect to our self-insurance and insurance policy deductibles. The projection of losses related to these liabilities requires actuarial assumptions that are subject to variability due to uncertainties regarding construction defect claims relative to differences in our markets and the types of product we build, insurance industry practices and legal or regulatory interpretations, among other factors. Key assumptions used in these estimates include claim frequencies, severities and settlement patterns, which can occur over an extended period of time.
Advertising Costs	Advertising Costs. We expense advertising costs as incurred.
Legal Fees	Legal Fees. Legal fees associated with litigation and similar proceedings that are not expected to provide a benefit in future periods are generally expensed as incurred. Legal fees associated with land acquisition and development and other activities that are expected to provide a benefit in future periods are capitalized as incurred in our consolidated balance sheets.
Stock-Based Compensation	Stock-Based Compensation. We measure and recognize compensation expense associated with our grant of equity-based awards at an amount equal to the fair value of share-based payments granted under compensation arrangements over the vesting period. We estimate the fair value of stock options and SARs granted using the Black-Scholes option-pricing model with assumptions based primarily on historical data. We report the tax benefit resulting from tax deductions in excess of the compensation expense recognized for stock options and SARs in our consolidated statements of cash flows as an operating cash outflow and a financing cash inflow.
Income Taxes	Income Taxes. The provision for, or benefit from, income taxes is calculated using the asset and liability method, under which deferred tax assets and liabilities are recorded based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Deferred tax assets are evaluated on a quarterly basis to determine if adjustments to the valuation allowance are required. This evaluation is based on the consideration of all available positive and negative evidence using a “more likely than not” standard with respect to whether deferred tax assets will be realized. The ultimate realization of our deferred tax assets depends primarily on our ability to generate future taxable income during the periods in which the related temporary differences in the financial basis and the tax basis of the assets become deductible. The value of our deferred tax assets depends on applicable income tax rates.
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss. The accumulated balances of other comprehensive loss in the consolidated balance sheets as of November 30, 2015 and 2014 were comprised solely of adjustments recorded directly to accumulated other comprehensive loss related to our benefit plan obligations. Such adjustments are made annually as of November 30, when our benefit plan obligations are remeasured.
Earnings (Loss) Per Share	Earnings Per Share. We compute earnings per share using the two-class method, which is an allocation of earnings between the holders of common stock and a company’s participating security holders. Our outstanding nonvested shares of restricted stock contain non-forfeitable rights to dividends and, therefore, are considered participating securities for purposes of computing earnings per share pursuant to the two-class method. We had no other participating securities at November 30, 2015, 2014 or 2013.
Recent accounting pronouncements	Recent Accounting Pronouncements. In April 2014, the FASB issued Accounting Standards Update No. 2014-08, “Presentation of Financial Statements (Topic 205) and Property, Plant and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity” (“ASU 2014-08”), which raises the threshold for a disposal to qualify as a discontinued operation and requires new disclosures of both discontinued operations and certain other disposals that do not meet the new definition of a discontinued operation. It also allows an entity to present a discontinued operation even when it has continuing cash flows and significant continuing involvement with the disposed component. The amendments in ASU 2014-08 are effective prospectively for disposals (or classifications as held for sale) of components of an entity that occur within annual periods beginning on or after December 15, 2014, and interim periods within those years. Early adoption is permitted but only for disposals (or classifications as held for sale) that have not been reported in financial statements previously issued or available for issuance. We believe the adoption of this guidance will not have a material effect on our consolidated financial statements. In May 2014, the FASB issued Accounting Standards Update No. 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“ASU 2014-09”). The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Companies may use either a full retrospective or a modified retrospective approach to adopt ASU 2014-09. In August 2015, the FASB issued Accounting Standards Update No. 2015-14, “Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date,” which delayed the effective date of ASU 2014-09 by one year. ASU 2014-09, as amended, is effective for public companies for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. We are currently evaluating the potential impact of adopting this guidance on our consolidated financial statements. In June 2014, the FASB issued Accounting Standards Update No. 2014-12, “Compensation — Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period” (“ASU 2014-12”). The amendments in ASU 2014-12 require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. A reporting entity should apply existing guidance in ASC 718, as it relates to awards with performance conditions that affect vesting to account for such awards. The amendments in ASU 2014-12 are effective for annual periods and interim periods within those annual periods beginning after December 15, 2015. Early adoption is permitted. Entities may apply the amendments in ASU 2014-12 either: (a) prospectively to all awards granted or modified after the effective date; or (b) retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. We believe the adoption of this guidance will not have a material effect on our consolidated financial statements. In August 2014, the FASB issued Accounting Standards Update No. 2014-15, “Presentation of Financial Statements — Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern” (“ASU 2014-15”), which requires management to evaluate, in connection with preparing financial statements for each annual and interim reporting period, whether there are conditions or events, considered in the aggregate, that raise substantial doubt about an entity’s ability to continue as a going concern within one year after the date that the financial statements are issued (or within one year after the date that the financial statements are available to be issued when applicable) and provide related disclosures. ASU 2014-15 is effective for the annual period ending after December 15, 2016, and for annual and interim periods thereafter. Early adoption is permitted. We believe the adoption of this guidance will not have a material effect on our consolidated financial statements. In January 2015, the FASB issued Accounting Standards Update No. 2015-01, “Income Statement — Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items” (“ASU 2015-01”). ASU 2015-01 eliminates the concept of extraordinary items from GAAP but retains the presentation and disclosure guidance for items that are unusual in nature or occur infrequently and expands the guidance to include items that are both unusual in nature and infrequently occurring. ASU 2015-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015. A reporting entity may apply ASU 2015-01 prospectively. A reporting entity may also apply ASU 2015-01 retrospectively to all periods presented in the financial statements. We believe the adoption of this guidance will not have a material effect on our consolidated financial statements. In February 2015, the FASB issued Accounting Standards Update No. 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis” (“ASU 2015-02”). ASU 2015-02 changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. ASU 2015-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2015. Early adoption is permitted, including adoption in an interim period. We believe the adoption of this guidance will not have a material effect on our consolidated financial statements. In April 2015, the FASB issued Accounting Standards Update No. 2015-03, “Interest — Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs” (“ASU 2015-03”). ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. For public entities, ASU 2015-03 is effective for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted for financial statements that have not been previously issued. ASU 2015-03 is to be applied on a retrospective basis and represents a change in accounting principle. We believe the adoption of this guidance will not have a material effect on our consolidated financial statements. In August 2015, the FASB issued Accounting Standards Update No. 2015-15, “Interest — Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements — Amendments to SEC Paragraphs Pursuant to Staff Announcement at June 18, 2015 EITF Meeting” (“ASU 2015-15”), which clarifies the treatment of debt issuance costs from line-of-credit arrangements after the adoption of ASU 2015-03. In particular, ASU 2015-15 clarifies that the SEC staff would not object to an entity deferring and presenting debt issuance costs related to a line-of-credit arrangement as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of such arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. We believe the adoption of this guidance will not have a material effect on our consolidated financial statements.
Reclassifications	Reclassifications. Certain amounts in our consolidated financial statements of prior years have been reclassified to conform to the current period presentation.
Segment Reporting	As of November 30, 2015, we had identified five operating reporting segments, comprised of four homebuilding reporting segments and one financial services reporting segment, within our consolidated operations. As of November 30, 2015, our homebuilding reporting segments conducted ongoing operations in the following states: West Coast: California Southwest: Arizona and Nevada Central: Colorado and Texas Southeast: Florida, Maryland, North Carolina and Virginia Our homebuilding reporting segments are engaged in the acquisition and development of land primarily for residential purposes and offer a wide variety of homes that are designed to appeal to first-time, move-up and active adult homebuyers. Our homebuilding operations generate most of their revenues from the delivery of completed homes to homebuyers. They also earn revenues from the sale of land. Our homebuilding reporting segments were identified based primarily on similarities in economic and geographic characteristics, product types, regulatory environments, methods used to sell and construct homes and land acquisition characteristics. We evaluate segment performance primarily based on segment pretax results. Our financial services reporting segment offers property and casualty insurance and, in certain instances, earthquake, flood and personal property insurance to our homebuyers in the same markets as our homebuilding reporting segments, and provides title services in the majority of our markets located within our Central and Southeast homebuilding reporting segments. This segment earns revenues primarily from insurance commissions and from the provision of title services. Prior to July 21, 2014, this segment also earned revenues pursuant to the terms of a marketing services agreement with Nationstar, under which Nationstar was our preferred mortgage lender and offered mortgage banking services, including mortgage loan originations, to our homebuyers who elected to use the lender. Since July 21, 2014, we have offered mortgage banking services, including mortgage loan originations, to our homebuyers indirectly through HCM, a joint venture of a subsidiary of ours and a subsidiary of Nationstar. Through these respective subsidiaries, we have a 49.9% ownership interest and Nationstar has a 50.1% ownership interest in HCM, with Nationstar providing management oversight of HCM’s operations. Our homebuyers may select any lender of their choice to obtain mortgage financing for the purchase of a home. Corporate and other is a non-operating segment that develops and oversees the implementation of company-wide strategic initiatives and provides support to our reporting segments by centralizing certain administrative functions. Corporate and other includes general and administrative expenses related to operating our corporate headquarters. A portion of the expenses incurred by Corporate and other is allocated to our homebuilding reporting segments. Our segments follow the same accounting policies used for our consolidated financial statements as described in Note 1. Summary of Significant Accounting Policies. The results of each segment are not necessarily indicative of the results that would have occurred had the segment been an independent, stand-alone entity during the periods presented, nor are they indicative of the results to be expected in future periods.
Inventory Impairment	Each community or land parcel in our owned inventory is assessed to determine if indicators of potential impairment exist. Impairment indicators are assessed separately for each community or land parcel on a quarterly basis and include, but are not limited to, the following: significant decreases in net orders, average selling prices, volume of homes delivered, gross profit margins on homes delivered or projected gross profit margins on homes in backlog or future deliveries; significant increases in budgeted land development and home construction costs or cancellation rates; or projected losses on expected future land sales. If indicators of potential impairment exist for a community or land parcel, the identified asset is evaluated for recoverability.
Land under Option Arrangements	Our inventory controlled under land option contracts and other similar contracts is assessed to determine whether it continues to meet our internal investment and marketing standards. Assessments are made separately for each optioned land parcel on a quarterly basis and are affected by the following factors relative to the market in which the asset is located, among others: current and/or anticipated net orders, average selling prices and volume of homes delivered; estimated land development and home construction costs; and projected profitability on expected future housing or land sales. When a decision is made not to exercise certain land option contracts and other similar contracts due to market conditions and/or changes in our marketing strategy, we write off the related inventory costs, including non-refundable deposits and unrecoverable pre-acquisition costs. Based on the re
Financial services [Member]
Segment Reporting Information [Line Items]
Operations	Financial Services Operations. Our financial services reporting segment generates revenues primarily from insurance commissions and title services. These operations also earned marketing services fees, pursuant to a marketing services agreement with a preferred lender, until July 21, 2014. Marketing services fees were recognized when earned. Insurance commissions are recognized when policies are issued. Title services revenues are recorded when closing services are rendered and title insurance policies are issued, both of which generally occur at the time each applicable home is closed.