Segment Reporting [Abstract] Financial services income loss Financial Services Income Loss [Table Text Block] Financial services income loss. Financial services assets liabilities Financial Services Assets Liabilities [Table Text Block] Financial services assets liabilities. Payables and Accruals [Abstract] Construction defect and other litigation liabilities Construction Defect and Other Litigation Liabilities Construction defect and other litigation liabilities. Employee compensation and related benefits Accrued Employee Benefits Warranty liability Standard Product Warranty Accrual Accrued interest payable Interest Payable Liabilities related to inventory not owned Liabilities Related to Inventory Not Owned Liabilities related to inventory not owned. Real estate and business taxes Taxes Payable Other Other Accrued Liabilities Total Accrued Liabilities Document and Entity Information [Abstract] Document and entity information. Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Voluntary Filers Entity Voluntary Filers Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Filer Category Entity Filer Category Entity Public Float Entity Public Float Entity Common Stock Shares Outstanding Entity Common Stock, Shares Outstanding Guarantees [Abstract] Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] KB Home Corporate Parent Company [Member] Guarantor Subsidiaries Guarantor Subsidiaries [Member] Non-Guarantor Subsidiaries Non-Guarantor Subsidiaries [Member] Consolidating Adjustments Consolidation, Eliminations [Member] Guarantor Obligations [Line Items] Guarantor Obligations [Line Items] Condensed Consolidated Balance Sheets Statement of Financial Position [Abstract] Assets Assets [Abstract] Cash and cash equivalents Cash and Cash Equivalent Excluding Financial Services Cash and Cash Equivalents Cash and cash equivalent excluding financial services cash and cash equivalent. Restricted cash Restricted Cash and Cash Equivalents Receivables Accounts and Notes Receivable, Net Inventories Inventory, Real Estate Investments in unconsolidated joint ventures Equity Method Investments Other assets Other Assets Total homebuilding assets Assets, Homebuilding Assets, homebuilding. Financial services Assets, Financial Services Assets, financial services. Investments in subsidiaries Investments in subsidiaries Investments in subsidiaries. Total assets Assets Liabilities and stockholders' equity Liabilities and Equity [Abstract] Accounts payable, accrued expenses and other liabilities Accounts Payable and Accrued Liabilities Mortgages and notes payable Notes and Loans Payable Total Homebuilding Liabilities, Homebuilding Liabilities, homebuilding. Financial services Financial Services Liabilities Intercompany Intercompany Adjustments Intercompany adjustments. Stockholder's equity Stockholders' Equity Attributable to Parent Total liabilities and Stockholders' equity Liabilities and Equity Equity [Abstract] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Condensed Consolidated Statements of Operations Condensed Consolidated Statements of Operations [Table Text Block] Condensed consolidated statements of operations. Condensed Consolidated Balance Sheets Condensed Consolidated Balance Sheets [Table Text Block] Condensed consolidated balance sheets. Condensed Consolidated Statements of Cash Flows Condensed Consolidated Statements of Cash Flows [Table Text Block] Condensed consolidated statements of cash flows. Supplemental Cash Flow Information [Abstract] Supplemental disclosures to the consolidated statements of cash flows Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Fair Value Disclosures [Abstract] Fair Value Disclosures Fair Value Disclosures [Text Block] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Parent [Member] Parent [Member] Common Stock Common Stock [Member] Grantor Stock Ownership Trust Grantor Stock Ownership Trust [Member] Grantor stock ownership trust. Treasury Stock Treasury Stock [Member] Paid-in Capital Additional Paid-in Capital [Member] Retained Earnings Retained Earnings [Member] Accumulated Other Comprehensive Loss Accumulated Other Comprehensive Income (Loss) [Member] Statement [Line Items] Statement [Line Items] Balance Balance, Shares Shares, Issued Comprehensive loss: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Net loss Net Income (Loss) Attributable to Parent Postretirement benefits adjustment Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Total comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Dividends on common stock Dividends, Common Stock, Cash Employee stock options and other, Value Stock Issued During Period, Value, Stock Options Exercised Employee stock options and other, Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Restricted stock awards, Value Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Restricted stock awards, Shares Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Restricted stock amortization Adjustment to Additional Paid in Capital Restricted Stock Amortization Adjustment to additional paid in capital restricted stock amortization. Forfeited restricted stock, Value Stock Issued During Period, Value, Restricted Stock Award, Forfeitures Forfeited restricted stock, Shares Stock Issued During Period, Shares, Restricted Stock Award, Forfeited Stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Cash-settled stock appreciation rights exchange Adjustments to Additional Paid in Capital Cash Settled Stock Appreciation Rights Exchange Adjustments to additional paid in capital cash settled stock appreciation rights exchange. Grantor stock ownership trust, Value Stock Issued During Period, Value, Employee Stock Purchase Plan Grantor stock ownership trust, Shares Stock Issued During Period, Shares, Employee Stock Purchase Plans Treasury stock, Value Treasury Stock, Value, Acquired, Cost Method Treasury stock, Shares Treasury Stock, Shares, Acquired Balance Balance, Shares Inventory Disclosure [Abstract] Inventories Inventory Disclosure [Text Block] Subsequent Events [Abstract] Subsequent Event Subsequent Events [Text Block] Segment Information Segment Reporting Disclosure [Text Block] Income Tax Disclosure [Abstract] Component of income tax benefit (expense) in the consolidated statement of operations Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Current federal income tax benefit Current Federal Tax Expense (Benefit) Current state income tax benefit (expense) Current State and Local Tax Expense (Benefit) Current income tax benefit Current Income Tax Expense (Benefit) Deferred federal income tax benefit Deferred Federal Income Tax Expense (Benefit) Deferred state income tax benefit Deferred State and Local Income Tax Expense (Benefit) Deferred income tax benefit Deferred Income Tax Expense (Benefit) Federal income tax benefit Federal Income Tax Expense (Benefit), Continuing Operations State income tax benefit State and Local Income Tax Expense (Benefit), Continuing Operations Income tax benefit Income Tax Expense (Benefit) Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 1988 Employee Stock Plan Nineteen Eighty Eight Employee Stock Plan [Member] Nineteen eighty eight employee stock plan. Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share Based payments award terms of Award Share Based Compensation Arrangement by Share Based Payments Award Terms of Award Share based compensation arrangement by share based payments award terms of award. Stock option transactions Stock Option Transactions [Abstract] Stock option transactions. Options outstanding at beginning of year, Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options outstanding at beginning of year, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Granted, Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures Granted, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period Weighted Average Exercise Prices The weighted average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period. Exercised, Shares Exercised, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Weighted Average Exercise Prices The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period. Cancelled, Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Cancelled, Weighted Average Exercise Price Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Options outstanding at end of year, Options Options outstanding at end of year, Weighted Average Exercise Price Options exercisable at end of year, Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Options exercisable at end of period, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Options available for grant at end of year, Options Share Based Compensation Arrangement by Share Based Payment Award Options Available for Grant Share based compensation arrangement by share based payment award options available for grant. Inventory Impairments and Land Option Contract Abandonments [Abstract] Inventory impairments and land option contract abandonments. Discount Rate Used in Estimating Discounted Cash Flow [Table] Discount Rate Used in Estimating Discounted Cash Flow [Table] Discount rate used in estimating discounted cash flow. Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Discount Rate Used in Estimating Discounted Cash Flow [Line Items] Discount Rate Used in Estimating Discounted Cash Flow [Line Items] Discount rate used in estimating discounted cash flow. Fair Value Estimate Input at Average Selling Price Fair Value Estimate Input at Average Selling Price Fair value estimate input at average selling price. Fair Value Estimate Input at Sales for Period Fair Value Estimate Input At Delivery For Period Fair value estimate input at delivery for period. Discount Rate Used in Estimating Discounted Cash Flow Discount Rate Used in Estimating Discounted Cash Flow Discount rate used in estimating discounted cash flow. Inventory Impairments and Land Option Contract Abandonments (Textual) [Abstract] Inventory Impairments and Land Option Contract Abandonments (Textual) [Abstract] Inventory impairments and land option contract abandonments. Number of land parcels or communities evaluated for recoverability Number of Land Parcels or Communities Evaluated for Recoverability Number of land parcels or communities evaluated for recoverability. Pretax, noncash inventory impairment charges Inventory Write-down Number of land parcels or communities associated with non cash inventory impairment charges Number of Land Parcels or Communities Associated with Non Cash Inventory Impairment Charges Number of land parcels or communities associated with non cash inventory impairment charges. Post impairment fair value of land parcels or communities Post Impairment Fair Value of Land Parcels or Communities Post impairment fair value of land parcels or communities. Charges related to adjustment to the fair value of real estate Charges Related to Adjustment to Fair Value of Real Estate Charges related to adjustment to fair value of real estate. Aggregate carrying value of inventory impacted by pretax, noncash inventory impairment charges Aggregate Carrying Value of Inventory Impacted by Pretax Noncash Inventory Impairment Charges Aggregate carrying value of inventory impacted by pretax, noncash inventory impairment charges. Number of communities and various other land parcels impacted by pretax, noncash inventory impairment charges Number of Communities and Various Other Land Parcels Impacted by Pretax Noncash Inventory Impairment Charges Number of communities and various other land parcels impacted by pretax, noncash inventory impairment charges. Land option contract abandonment charges Land Option Contract Abandonment Charges Land option contract abandonment charges. Number of Lots on which abandonment charges are recognized Number of Lots on Which Abandonment Charges are Recognized Number of lots on which abandonment charges are recognized. Remaining useful life in addition to specified useful lives Remaining Useful Life Minimum Remaining useful life minimum. Specified period of remaining useful lives Remaining Useful Life Maximum Remaining useful life maximum. Expected realization period of inventory maximum Expected Realization Period of Inventory Maximum Expected realization period of inventory maximum. Inventory Impairments and Land Option Contract Abandonments Inventory Impairments and Land Option Contract Abandonments [Text Block] Inventory impairments and land option contract abandonments. Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, Disclosure Item Amounts [Domain] Fair Value, Disclosure Item Amounts [Domain] Carrying Value Carrying (Reported) Amount, Fair Value Disclosure [Member] Estimated Fair Value Estimate of Fair Value, Fair Value Disclosure [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value, Measurements, Fair Value Hierarchy [Domain] Level 2 Fair Value, Inputs, Level 2 [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Senior notes due 2011 at 6 3/8% Senior Notes Due Two Thousand Eleven at Six Point Three Seven Five Percent [Member] Senior notes due 2011 at 6 point 375 percent. Senior notes due February 1, 2014 at 5 3/4% Senior Notes Due Two Thousand Fourteen at Five Point Seven Five Percent [Member] Senior notes due 2014 at 5 point 75 percent. Senior notes due January 15, 2015 at 5 7/8% Senior Notes Due Two Thousand Fifteen at Five Point Eight Seven Five Percent [Member] Senior notes due 2015 at 5 point 875 percent. Senior notes due June 15, 2015 at 6 1/4% Senior Notes Due Two Thousand Fifteen at Six Point Two Five Percent [Member] Senior notes due 2015 at 6 point 25 percent. Senior notes due September 15, 2017 at 9.10% Senior Notes Due Two Thousand Seventeen at Nine Point One Percent [Member] Senior Notes Due 2017 at 9 Point 1 Percent. Senior notes due June 15, 2018 at 7 1/4% Senior Notes Due Two Thousand Eighteen at Seven Point Two Five Percent [Member] Senior notes due 2018 at 7 point 25 percent. Senior notes due March 15, 2020 at 8.00% Senior Notes Due Two Thousand Twenty at Eight Point Zero Zero Percent [Member] Senior notes due two thousand twenty at eight point zero zero percent. Senior notes due September 15, 2022 at 7.50% Senior Notes Due Two Thousand Twenty Two At Seven Point Five Zero Percent [Member] Senior notes due 2022 at 7 point 50 percent. Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Senior notes, rate Debt Instrument, Interest Rate, Stated Percentage Senior notes payable Notes Payable, Fair Value Disclosure Accounting Policies [Abstract] Basic and diluted loss per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Equity in (income) loss/(gain) on wind down of unconsolidated joint ventures Loss (Income) from Equity Method Investments Including Financial Services Loss (Income) from Equity Method Investments Loss (income) from equity method investments including financial services loss (income) from equity method investments. Distributions of earnings from unconsolidated joint ventures Proceeds from Equity Method Investment, Dividends or Distributions Loss on loan guaranty Loss on Loan Guaranty Loss on loan guaranty. Gain on sale of operating property Gain (Loss) on Sale of Property Amortization of discounts and issuance costs Amortization of Financing Costs and Discounts Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Provision for deferred income taxes Increase (Decrease) in Deferred Income Taxes Loss (gain) on early extinguishment of debt/loss on voluntary termination of revolving credit facility Write Off of Debt Issuance Costs on Termination of Revolving Credit Facility and Loss (Gain) on Early Extinguishment of Debt Amount represents the write off of amounts previously capitalized as debt issuance costs on termination of revolving credit facility and loss (gain) on early extinguishment of debt. Tax benefits from stock-based compensation Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Operating Activities Stock-based compensation Share-based Compensation Inventory impairments and land option contract abandonments Inventory Impairments and Land Option Contract Abandonments The charge against earnings resulting from the write-down of assets from their carrying value to their fair value. Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Receivables Increase (Decrease) in Accounts and Notes Receivable Inventories Increase (Decrease) in Inventories Accounts payable, accrued expenses and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Return of investments in (contributions to) unconsolidated joint ventures Payments to Acquire Interest in Joint Venture Proceeds from sale of operating property Proceeds from Sale of Property Held-for-sale Purchases of property and equipment, net Payments for (Proceeds from) Productive Assets Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Change in restricted cash Proceeds from (Repayments of) Restricted Cash, Financing Activities Proceeds from issuance of senior notes Proceeds from Issuance of Senior Long-term Debt Payment of senior notes issuance costs Payments of Debt Issuance Costs Repayment of senior notes Repayments of Senior Debt Payments on mortgages and land contracts due to land sellers and other loans Proceeds from (Repayments of) Secured Debt Issuance of common stock under employee stock plans Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options Excess tax benefit associated with exercise of stock options Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities Payments of cash dividends Payments of Ordinary Dividends, Common Stock Repurchases of common stock Payments for Repurchase of Common Stock Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Net increase (decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of year Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of year Financial services income loss Financial services income loss [Abstract] Financial services income loss. Financial services: Financial Services Revenue [Abstract] Insurance commissions Fees and Commissions Title services Title Services Title services. Marketing services fees Revenue, Other Financial Services Interest income Interest Income, Operating Total Financial Services Revenue Expenses Financial Services Costs [Abstract] Expenses Financial Services Costs Operating income Financial Services Operating Income Financial services operating income. Equity in income/gain on wind down of unconsolidated joint venture Equity in Income (Loss) of Unconsolidated Joint Venture, Financial Services Equity in income (loss) of unconsolidated joint venture, financial services. Financial services pretax income Income (Loss) Before Tax, Financial Services Income (loss) before tax, financial services. Financial services assets liabilities Financial Services Assets Liabilities [Abstract] Financial services assets liabilities. Cash and cash equivalents Cash and Cash Equivalents Financial Services Cash and cash equivalents related to financial services. Receivables Receivables Financial Services Receivables financial services. Investment in unconsolidated joint venture Investment in Unconsolidated Joint Venture Financial Services Investment in unconsolidated joint venture. Other assets Other Assets Financial Services Other assets financial services. Financial services Liabilities Liabilities [Abstract] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Financial Services Accounts payable and accrued liabilities financial services. Total liabilities Financial services (Textual) [Abstract] Financial Services (Textual) [Abstract] Financial services. Distribution received Proceeds from Divestiture of Interest in Joint Venture Receivable from wind down of KBA Mortgage Due from Related Parties Equity Method Investment, Realized Gain (Loss) on Disposal Equity Method Investment, Realized Gain (Loss) on Disposal Company's 2010 Plan Company's Two Thousand Ten Plan [Member] Company's two thousand ten plan. August 2010 Exchange Offer August Two Thousand Ten Exchange Offer [Member] August 2010 Exchange Offer. Employee Stock Option Employee Stock Option [Member] November 2010 Exchange Offer November Two Thousand Ten Exchange Offer [Member] November two thousand ten exchange offer. Phantom Share Units (PSUs) Phantom Share Units (PSUs) [Member] 2010 Equity Incentive Plan Equity Incentive Twenty Thousand Ten Plan [Member] Equity incentive twenty thousand ten plan. Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Saving Plan Saving Plan [Member] Saving plan. Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] Stock Options Stock Option [Member] Restricted Stock Restricted Stock [Member] Performance Shares Performance Shares [Member] Employee Benefit and Stock Plans (Textual) [Abstract] Employee Benefit and Stock Plans (Textual) [Abstract] Employee benefit and stock plans. Aggregate cost related to saving plan Defined Contribution Plan, Cost Recognized Net assets invested in funds consisting common stock Percentage of Plan Net Assets Invested in Company Common Stock Percentage of plan net assets invested in company common stock. Number of shares authorized for issuance of stock based awards to employees Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Grant of stock option, Reduce the plan share capacity Reduction of Plan Per Share Capacity for Grants of Stock Option and Other Similar Awards Reduction of plan per share capacity for grants of stock option and other similar Awards. Grant of restricted stock, Reduce the Plan share capacity Reduction of Plan Per Share Capacity for Grants of Restricted Stock and Other Similar Full Value Awards Reduction of plan per share capacity for grants of restricted stock and other similar full value awards. Number of additional shares authorized for issuance of stock based awards to employees Share Based Compensation Arrangement by Share Based Payment Award Additional Number of Shares Authorized Share based compensation arrangement by share based payment award additional number of shares authorized. Number of eligible employees returned SARs related to the exchange offer to the company Number of Eligible Employees Returned Stock Appreciation Rights Number of eligible employees returned stock appreciation rights. SARs returned to the company Share Based Compensation Arrangement by Share Based Payment Award Other than Options Return in Period Share based compensation arrangement by share based payment award other than options return in period. Number of Employees to purchase Company's common stock in exchange for corresponding grants of stock options Number of Employees to Purchase Company's Common Stock in Exchange for Corresponding Grants of Stock Options Number of Employees to purchase Company's common stock in exchange for corresponding grants of stock options. Common Stock Purchase by Employee Common Stock Purchase by Employee Common stock purchase by employee. Purchase price of common stock per share for 18 eligible employees Purchase Price of Common Stock Per Share for Eighteen Eligible Employees Purchase price of common stock per share for eighteen eligible employees. Shares purchase per employee Shares Purchase Per Employee Shares purchase per employee. Purchase price of common stock per share for 1 eligible employees Purchase Price of Common Stock Per Share for One Eligible Employees Purchase price of common stock per share for one eligible employees. Number of employees to whom stock options granted in exchange for stock appreciation rights Number of Employees to Whom Stock Options Granted in Exchange for Stock Appreciation Rights Number of employees to whom stock options granted in exchange for stock appreciation rights. Number of Employees to whom one grant of stock options to purchase Company's common stock Number of Employees to Whom One Grant of Stock Options to Purchase Company's Common Stock Number of employees to whom one grant of stock options to purchase company's common stock. Employees purchase company's common stock in exchange for corresponding grants of stock option Purchase price of common stock per share Purchase Price of Common Stock Per Share Purchase price of common stock per share. Purchase price of common stock per share for 7 eligible employees Purchase Price of Common Stock Per Share for Seven Eligible Employees Purchase price of common stock per share for seven eligible employees. Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Grant, award share percentage Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants, Award Share Percentage Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants, Award Share Percentage Minimum period of restriction imposed on share grant lapse Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Weighted average per share grant date fair value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Outstanding at end of year, Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Total unrecognized stock-based compensation expense related to unvested stock option awards Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Vesting period of vesting shares Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Vested in Full Share based compensation arrangement by share based payment award equity instrument other than options vested in full. SARs vest in equal annual installments period Stock Appreciation Rights Vested in Equal Annual Investment Stock appreciation rights vested in equal annual investment. Employee Benefit and Stock Plan (Additional Textual) [Abstract] Employee Benefit and Stock Plan (Additional Textual) [Abstract] Employee benefit and stock plan. Exercises in period, total intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value Exercises in period (in shares) Intrinsic value of stock options outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Intrinsic value of stock options exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Performance-based stock options to purchase an aggregate shares of company's common stock Purchase Aggregate Share of Company's Common Stock Under Performance Based Stock Options Purchase aggregate share of company's common stock under performance based stock options. Company's common stock at the purchase price per share Company Common Stock at the Purchase Price Per Share Company's common stock at the purchase price per share. Grant-date fair value per performance-based stock option Fair Value of Per Performance Based Stock Option Fair value of per performance based stock option. Weighted average fair value of stock options granted Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Stock-based compensation expense related to stock option grants Allocated Share-based Compensation Expense Tax shortfall from cancellation of stock awards Tax Shortfall From Cancellation of Stock Awards Tax shortfall from cancellation of stock awards. Excess Tax Benefit (Tax Deficiency) from Share-based Compensation, Financing Activities Recognized compensation expense related to various stock Recognized Compensation Expense Related to Various Stock Recognized compensation expense related to various stock. Shares of common stock held in trust Common Stock, Shares Held in Employee Trust, Shares Receivables [Abstract] Allowances for doubtful accounts Allowance for Doubtful Accounts Receivable Condensed Consolidated Statements of Operations Income Statement [Abstract] Revenues Revenues Homebuilding: Real Estate Revenue, Net [Abstract] Revenues Home Building Revenue Construction and land costs Construction and Development Costs Selling, general and administrative expenses Selling, General and Administrative Expense Operating income (loss) Operating Income (Loss) Interest income Investment Income, Interest Interest expense Write Off of Debt Issuance Costs and Interest Expense Net of Amounts Capitalized Write off of debt issuance costs and interest expense net of amounts capitalized. Equity in income (loss) of unconsolidated joint ventures Income (Loss) from Equity Method Investments Homebuilding pretax loss Income (Loss) Before Tax, Homebuilding Income (loss) before tax, homebuilding. Financial services pretax income Total pretax loss Income (Loss) from Continuing Operations before Income Taxes, Domestic Income tax benefit Equity in net loss of subsidiaries Equity in net Loss of Subsidiaries Equity in net loss of subsidiaries. Income tax benefit computed at the statutory U.S. federal income tax rate and income tax benefit (expense) provided in the consolidated statements of operations Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract] Income tax benefit computed at statutory rate Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate Increase (decrease) resulting from Increase Decrease Resulting from Other Reconciling Items [Abstract] Increase decrease resulting from other reconciling items. State taxes, net of federal income tax benefit Income Tax Reconciliation, State and Local Income Taxes Reserve and deferred income Income Tax Reconciliation Change Reserve Deferred Income Income tax reconciliation change reserve and deferred income. Capitalized expenses Income Tax Reconciliation Capitalized Expenses Income tax reconciliation capitalized expenses. Basis in joint ventures Income Tax Reconciliation Equity in Earnings Losses of Unconsolidated Joint Ventures Income tax reconciliation equity in earnings losses of unconsolidated joint ventures. NOLs reconciliation Income Tax Reconciliation Change Net Operating Loss Income tax reconciliation change in net operating loss. Inventory impairments Income Tax Reconciliation, Inventory Impairments Income Tax Reconciliation, Inventory Impairments Recognition of federal tax benefits Recognition of Federal Tax Benefits Recognition of federal tax benefits. Tax credits Income Tax Reconciliation, Tax Credits Valuation allowance for deferred tax assets Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance Other, net Income Tax Reconciliation, Other Adjustments Reconciliation of the beginning and ending balances of the gross unrecognized benefits Reconciliation of the Beginning and Ending Balances of the Gross Unrecognized Benefit [Abstract] Reconciliation of the beginning and ending balances of the gross unrecognized benefit. Balance at beginning of year Unrecognized Tax Benefits Additions for tax positions related to prior years Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions Reductions for tax positions related to prior years Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions Reductions related to settlement Unrecognized Tax Benefits Decreases Resulting From Settlements Unrecognized tax benefits decreases resulting from settlements. Reductions due to lapse of statute of limitations Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations Reductions due to resolution of federal and state audits Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities Balance at the end of year Statement, Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Inventories Inventory, Operative Builders Investments in unconsolidated joint ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Homebuilding assets Total assets Accounts payable Accounts Payable Accrued expenses and other liabilities Homebuilding liabilities Stockholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock - $1.00 par value; authorized 10,000,000 shares; none issued Preferred Stock, Value, Issued Common stock - $1.00 par value; authorized, 290,000,000 shares at November 30, 2012 and 2011; 115,178,187 and 115,170,693 shares issued at November 30, 2012 and 2011, respectively Common Stock, Value, Issued Paid-in capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Grantor stock ownership trust, at cost: 10,615,934 and 10,884,151 shares at November 30, 2012 and 2011, respectively Common Stock Issued, Employee Stock Trust Treasury stock, at cost: 27,340,468 and 27,214,174 shares at November 30, 2012 and 2011, respectively Treasury Stock, Value Total stockholder's equity Total liabilities and stockholders' equity Other Assets [Abstract] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Other Assets [Line Items] Other Assets [Line Items] Other Assets [Line Items] Cash surrender value of insurance contracts Cash Surrender Value of Life Insurance Property and equipment, net Property, Plant and Equipment, Net Debt issuance costs Deferred Finance Costs, Net Prepaid expenses Prepaid Expense Net deferred tax assets Deferred Tax Assets, Net Total Senior notes Debt Instrument, Face Amount Supplemental Guarantor Information Guarantees [Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Mortgages and land contracts due to land sellers and other loans (6% to 7% at November 30, 2012 and 2011) Mortgages and Land Contracts Due to Land Sellers and Other Loans [Member] Mortgages and land contracts due to land sellers and other loans. Debt Instrument [Line Items] Debt Instrument [Line Items] Mortgages and Notes Payable Debt Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Subsequent Event (Textual) [Abstract] Subsequent Event (Textual) [Abstract] Subsequent event. Components of deferred tax liabilities and assets Components of Deferred Tax Assets and Liabilities [Abstract] Deferred tax liabilities Components of Deferred Tax Liabilities [Abstract] Capitalized expenses Deferred Tax Liabilities, Deferred Expense State taxes Deferred Tax Liabilities, Tax Deferred Income Other Deferred Tax Liabilities, Other Total Deferred Tax Liabilities, Net Deferred tax assets: Components of Deferred Tax Assets [Abstract] Inventory impairments and land option contract abandonments Deferred Tax Assets Inventory Impairments and Land Option Contract Abandonments Deferred tax assets inventory impairments and land option contract abandonments. NOL from 2006 through 2012 Deferred Tax Assets, Operating Loss Carryforwards Warranty, legal and other accruals Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals Employee benefits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Benefits Partnerships and joint ventures Deferred Tax Assets, Equity Method Investments Depreciation and amortization Deferred Tax Assets Depreciation and Amortization Deferred tax assets depreciation and amortization. Capitalized expenses Deferred Tax Assets Capitalized Expenses Deferred tax assets capitalized expenses. Tax credits Deferred Tax Assets, Tax Credit Carryforwards Deferred income Deferred Tax Assets, Deferred Income Other Deferred Tax Assets, Other Total Deferred Tax Assets, Gross Valuation allowance Deferred Tax Assets, Valuation Allowance Total Deferred Tax Assets, Net of Valuation Allowance Net deferred tax assets Ownership share in guarantor subsidiaries Ownership Share in Guarantor Subsidiaries Ownership share in guarantor subsidiaries. Equity Method Investments and Joint Ventures [Abstract] Investments in Unconsolidated Joint Ventures Investments in Unconsolidated Joint Ventures [Text Block] Investments in unconsolidated joint ventures. Quarterly Financial Data [Abstract] Consolidated quarterly results Schedule of Quarterly Financial Information [Table Text Block] Schedule of significant unobservable inputs Fair Value, Measurement Inputs, Disclosure [Text Block] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Equity Method Investee, Name [Axis] Equity Method Investee, Name [Axis] Equity Method Investee, Name [Domain] Equity Method Investee, Name [Domain] South Edge Investments in Unconsolidated Joint Ventures with South Edge Debt [Member] Investments in unconsolidated joint ventures with south edge debt. Investments in Unconsolidated Joint Ventures with Debt Investments in Unconsolidated Joint Ventures with Debt [Member] Investments in unconsolidated joint ventures with other debt. Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Number of investments in unconsolidated joint ventures Number of Investments in Unconsolidated Joint Ventures Number of investments in unconsolidated joint ventures. Basic and diluted loss per share Earnings Per Share, Basic and Diluted [Abstract] Numerator: Net Income (Loss) Available to Common Stockholders, Diluted [Abstract] Denominator: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic and diluted average shares outstanding Weighted Average Number of Shares Outstanding, Basic and Diluted Basic and diluted loss per share Earnings Per Share, Basic and Diluted Other Assets Other Assets [Text Block] Other assets. Variable Interest Entities [Abstract] Variable interest entities. Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Cash deposits associated with land option and other similar contracts of unconsolidated VIE's Cash Deposits Associated with Land Option and Other Similar Contracts of Unconsolidated Variable Interest Entities Cash deposits associated with land option and other similar contracts of unconsolidated variable interest entities. Aggregate purchase price of land option and other similar contracts of unconsolidated VIE's Purchase Price Associated with Land Option and Other Similar Contracts of Unconsolidated Variable Interest Entities Purchase price associated with land option and other similar contracts of unconsolidated variable interest entities. Total cash deposits associated with land option and other similar contracts that were not VIE's Cash Deposits Associated with Land Option and Other Similar Contracts of Non Variable Interest Entities Cash deposits associated with land option and other similar contracts of non variable interest entities. Aggregate purchase price of land option and other similar contracts that were not VIE's Purchase Price Associated with Land Option and Other Similar Contracts of Non Variable Interest Entities Purchase price associated with land option and other similar contracts of non variable interest entities. Non refundable deposits related to land option and other similar contracts Cash Deposits on Land Option and Other Similar Contracts Cash deposits on land option and other similar contracts. Aggregate Purchase Price Associated with Land Option and Other Similar Contracts Aggregate Purchase Price Associated with Land Option and Other Similar Contracts Aggregate purchase price associated with land option and other similar contracts. Preacquisition costs on land option contracts and other similar contracts preacquisition costs on land option contracts and other similar contracts preacquisition costs on land option contracts and other similar contracts Outstanding letters of credit Outstanding Letters of Credit in Lieu of Cash Deposits under Certain Land Option or Other Similar Contracts Outstanding letters of credit in lieu of cash deposits under certain land option or other similar contracts. Increase in inventories and accrued expenses and other liabilities Increase in Inventories and Accrued Expenses and Other Liabilities Due to Land Option and Other Similar Contracts Increase in inventories and accrued expenses and other liabilities due to land option and other similar contracts. Financial information relating to company reporting segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Stockholder's Equity (Textual) [Abstract] Stockholders' Equity (Textual) [Abstract] Stockholders' equity. Number of shares that can be purchased by exercising each right Convertible Preferred Stock, Shares Issued upon Conversion Purchase price for right holders Purchase Price Right Holders Purchase price for right holders. Exercisable options available Conditions on Periods During Which Rights to be Exercised Conditions on periods during which rights to be exercised. Calendar days after a public announcement during which rights to be exercised Calendar Days after a Public Announcement During which Rights to be Exercised Calendar days after a public announcement during which rights to be exercised. Business days after the commencement of a tender or exchange offer during which rights to be exercised Business Days after the Commencement of a Tender or Exchange Offer During which Rights to be Exercised Business days after the commencement of a tender or exchange offer during which rights to be exercised. Beneficially ownership in company's outstanding common stock to be held by person or group to exercise rights Beneficially Ownership in Company's Outstanding Common Stock to be Held by Person or Group to Exercise Rights Beneficially ownership in company's outstanding common stock to be held by person or group to exercise rights. Price at which company may redeem all of the then outstanding rights Class of Warrant or Right, Exercise Price of Warrants or Rights Options under which right issued pursuant to the 2009 rights Agreement will expire Conditions on Periods During Which Rights Issued Pursuant to the Two Thousand Nine Rights Agreement will Expire Conditions on periods during which rights issued pursuant to the two thousand nine rights agreement will expire. Authorized repurchase of common stock Stock Repurchase Program, Number of Shares Authorized to be Repurchased Cash dividend declared per share Common Stock, Dividends, Per Share, Declared Employee Benefit and Stock Plans Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Level 3 Fair Value, Inputs, Level 3 [Member] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Nonrecurring Fair Value, Measurements, Nonrecurring [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets measured at fair value on a nonrecurring basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract] Long-lived assets held and used Long-lived Assets Held and Used Fair Value Disclosure Long lived assets held and used fair value disclosure. Mortgages and Notes Payable Schedule of Long-term Debt Instruments [Table Text Block] Statements of Operations of Unconsolidated Joint Ventures Equity Method Investment, Summarized Financial Information, Income Statement [Abstract] Revenues Equity Method Investment, Summarized Financial Information, Revenue Construction and land costs Equity Method Investment, Summarized Financial Information, Construction and Land Costs Equity method investment summarized financial information construction and land costs. Other expense, net Equity Method Investment, Summarized Financial Information, Other Income Expenses, Net Equity method investment summarized financial information other income expenses net. Income (loss) Equity Method Investment, Summarized Financial Information, Net Income (Loss) Assets Equity Method Investment, Summarized Financial Information, Assets [Abstract] Cash Equity Method Investment, Summarized Financial Information, Cash Equity method investment summarized financial information cash. Receivable Equity Method Investment, Summarized Financial Information, Receivable Equity method investment summarized financial information receivable. Inventories Equity Method Investment, Summarized Financial Information, Inventories Equity method investment summarized financial information inventories. Other assets Equity Method Investment, Summarized Financial Information, Other Assets Equity method investment summarized financial information other assets. Total assets Equity Method Investment, Summarized Financial Information, Assets Liabilities and equity Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract] Accounts payable and other liabilities Equity Method Investment, Summarized Financial Information, Accounts Payable and Other Liabilities Equity method investment summarized financial information accounts payable and other liabilities. Equity Equity Method Investment, Summarized Financial Information, Equity or Capital Total liabilities and equity Equity Method Investment, Summarized Financial Information, Liabilities and Equity Operations Operations [Policy Text Block] Operations. Basis of Presentation Basis of Presentation [Policy Text Block] Basis of presentation. Use of Estimates Use of Estimates, Policy [Policy Text Block] Cash and Cash Equivalents and Restricted Cash Cash and Cash Equivalents, Policy [Policy Text Block] Property and Equipment, Operating Properties and Depreciation Property, Plant and Equipment, Policy [Policy Text Block] Homebuilding Operations Revenue Recognition, Real Estate Transactions, Policy [Policy Text Block] Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Financial Services Operations Financial Services Operations [Policy Text Block] Financial services operations. Warranty Costs Standard Product Warranty, Policy [Policy Text Block] Insurance Insurance [Policy Text Block] Insurance. Advertising Costs Advertising Costs, Policy [Policy Text Block] Legal Fees Legal Costs, Policy [Policy Text Block] Stock-Based Compensation Compensation Related Costs, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Accumulated Other Comprehensive Loss Comprehensive Income (Loss) Note [Text Block] Loss Per Share Earnings Per Share, Policy [Policy Text Block] New Accounting Pronouncements and Changes in Accounting Principles [Text Block] New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Recent accounting pronouncements Description of New Accounting Pronouncements Not yet Adopted [Text Block] Reclassifications Reclassifications [Policy Text Block] Reclassifications. Accounting Standards Codification Topic No.280, Segment Reporting Segment Reporting, Policy [Policy Text Block] Accounting Standards Codification Topic No.810,Consolidation (ASC 810) Consolidation, Policy [Policy Text Block] Accrued Expenses and Other Liabilities Accounts Payable and Accrued Liabilities Disclosure [Text Block] Compensation and Retirement Disclosure [Abstract] Postretirement Benefits Additional (Textual) [Abstract] Postretirement Benefits Additional (Textual) [Abstract] Postretirement benefits. Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Amortization of unrecognized loss cost Defined Benefit Plan, Amortization of Gains (Losses) Plan settlement cost Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements Other income that partly offset net periodic benefit cost Other Income that Partly Offset Net Periodic Benefit Cost Other income that partly offset net periodic benefit. Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Other cost Defined Benefit Plan, Other Costs Liabilities related to postretirement benefit plan Pension and Other Postretirement Defined Benefit Plans, Liabilities Discounted rate for benefit plan Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Supplemental Nonqualified Unfunded Retirement Plan Supplemental Nonqualified Unfunded Retirement Plan [Member] Supplemental nonqualified unfunded retirement plan. Unfunded Death Benefit Plan Unfunded Death Benefit Plan [Member] Unfunded death benefit plan. Kb Home Retirement Plan and Kb Home Supplemental Executive Officer Under Kb Home Retirement Plan Kb Home Retirement Plan and Kb Home Supplemental Executive Officer Under Kb Home Retirement Plan [Member] Kb home retirement plan and kb home supplemental executive officer under kb home retirement plan. Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Cash surrender value of insurance contracts under KB Home Retirement Plan Cash Surrender Value of Insurance Contracts Cash surrender value of insurance contracts. Benefits paid Defined Benefit Plan, Benefits Paid 2013 Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months 2014 Defined Benefit Plan, Expected Future Benefit Payments, Year Two 2015 Defined Benefit Plan, Expected Future Benefit Payments, Year Three 2016 Defined Benefit Plan, Expected Future Benefit Payments, Year Four 2017 Defined Benefit Plan, Expected Future Benefit Payments, Year Five 2018 - 2022 Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter Long-lived assets held and used, Carrying Value Carrying Amount of Long Lived Assets Held and used Written Down to Fair Value Carrying amount of long-lived assets held and used written down to fair value. Post Impairment Fair Value of Land Parcels or Communities Total inventory impairments Schedule Of Share Based Compensation Shares Authorized Under Stock Option Plans By Exercise Price Range [Table] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Axis] Exercise Price Range [Axis] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] $ 6.32 to $10.54 Range One [Member] Range one. $10.55 to $14.96 Range Two [Member] Range two. $14.97 to $20.08 Range Three [Member] Range three. $20.09 to $33.92 Range Four [Member] Range four. $33.93 to $69.63 Range Five [Member] Range five. $ 6.32 to $69.63 Range Six [Member] Range six. Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Stock options outstanding and stock options exercisable Share Based Compensation Shares Authorized Under Stock Option Plans by Exercise Price Range [Abstract] Share based compensation shares authorized under stock option plans by exercise price range. Range of Exercise Price, Minimum Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit Range of Exercise Price, Maximum Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit Options Outstanding, Options Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options Options Outstanding, Weighted Average Exercise Price Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price Options Outstanding, Weighted Average Remaining Contractual Life Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term Options Exercisable, Options Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options Options Exercisable, Weighted Average Exercise Price Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Options Exercisable, Weighted Average Remaining Contractual Life Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term Income Taxes Income Tax Disclosure [Text Block] Assumptions of Black-Scholes option-pricing model Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected volatility factor Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected term Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Legal Matters [Abstract] Legal Matters [Abstract] Legal Matters Legal Matters and Contingencies [Text Block] Total revenues Operating loss Equity in loss of unconsolidated joint ventures Homebuilding pretax loss Revenues Total pretax loss Net loss Quarterly Results (unaudited) Quarterly Financial Information [Text Block] Inventories Inventories [Table Text Block] Inventories. Interest costs Interest Costs [Table Text Block] Interest costs. Senior Subordinate Notes Senior Subordinate Notes [Member] Senior subordinate notes. Senior notes due September 15, 2017 Senior Notes Due Fifteen September Two Thousand Seventeen [Member] Senior notes due fifteen September two thousand seventeen. Senior notes under the 2008 shelf registration Senior Notes Under the Two Thousand Eight Shelf Registration [Member] Senior notes under the 2008 shelf registration. Senior Notes Private Placement Senior Notes Private Placement [Member] Senior notes private placement. Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount Cash maintained at LOC facilities Letter of Credit Facility Collateral Amount, Included in Restricted Cash Amount of collateral that secures the outstanding letters of credit, included in restricted cash. Gain on early extinguishment of debt Gains (Losses) on Extinguishment of Debt Primarily inventories carrying value Primarily Inventories Carrying Value Primarily inventories carrying value. Percentage of principal amount in relation to issued value of senior notes Percentage of Principal Amount in Relation to Issued Value of Senior Notes Percentage of principal amount in relation to issued value of senior notes. Total consideration paid to purchase the notes Repayments of Long-term Debt Repayment of aggregate principal amount of senior notes Repayment of Aggregate Principal Amount of Senior Notes Repayment of aggregate principal amount of senior notes. Percentage of principal amount for purchase of notes if change in control Percentage of Principal Amount for Purchase of Notes if Change in Control Percentage of principal amount for purchase of notes if change in control. Long-term Debt, Fiscal Year Maturity [Abstract] Long-term Debt, Fiscal Year Maturity [Abstract] Principal payments on senior notes, mortgages and land contracts due to land sellers and other loans due 2013 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months Principal payments on senior notes, mortgages and land contracts due to land sellers and other loans due 2014 Long-term Debt, Maturities, Repayments of Principal in Year Two Principal payments on senior notes, mortgages and land contracts due to land sellers and other loans due 2015 Long-term Debt, Maturities, Repayments of Principal in Year Three Principal payments on senior notes, mortgages and land contracts due to land sellers and other loans due 2016 Long-term Debt, Maturities, Repayments of Principal in Year Four Principal payments on senior notes, mortgages and land contracts due to land sellers and other loans due 2017 Long-term Debt, Maturities, Repayments of Principal in Year Five Principal payments on senior notes, mortgages and land contracts due to land sellers and other loans due thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Accrued Expenses and Other Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] KBA Mortgage KBA Mortgage [Member] KBA Mortgage [Member] Statement, Business Segments [Axis] Business Segments [Axis] Segment [Domain] Segment [Domain] West Coast West Coast [Member] West coast. Southwest Southwest [Member] Southwest. Central Central [Member] Central. Southeast Southeast [Member] Southeast. Corporate and Other Corporate and Other [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Ownership interest in joint venture Equity Method Investment, Ownership Percentage Revenues: Segment Reporting Information, Revenue for Reportable Segment [Abstract] Total homebuilding revenues Financial services Total revenues Pretax income (loss): Pretax Income Loss [Abstract] Pretax income loss. Total homebuilding pretax loss Financial services Equity in income (loss) of unconsolidated joint ventures: Equity in Income (Loss) of Unconsolidated Joint Ventures [Abstract] Equity in income loss of unconsolidated joint ventures. Total equity in income (loss) of unconsolidated joint ventures Inventory impairments: Inventory Impairments [Abstract] Inventory impairments. Land option contract abandonments: Land Option Contract Abandonments [Abstract] Land option contract abandonments. Total land option contract abandonment charges Joint venture impairments: Joint Venture Impairments [Abstract] Joint venture impairments. Total joint venture impairments Other than Temporary Impairment Losses, Investments Assets: Investments in unconsolidated joint ventures: Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures [Abstract] Restricted stock transactions Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Outstanding at beginning of year, Shares Outstanding at beginning of year, Weighted Average per Share Grant Date Fair Value Granted, Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Granted, Weighted Average per Share Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Vested, Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Vested, Weighted Average per Share Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Cancelled, Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Cancelled, Weighted Average per Share Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Outstanding at end of year, Weighted Average per Share Grant Date Fair Value Other Assets Schedule of Other Assets [Table Text Block] Income Tax Contingency [Table] Income Tax Contingency [Table] Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Investment Tax Credit Carryforward, Expiration in 2026 [Member] Investment Tax Credit Carryforward, Expiration in 2026 [Member] Investment Tax Credit Carryforward, Expiration in 2026 [Member] Investment Tax Credit Carryforward, Expiration in 2027 [Member] Investment Tax Credit Carryforward, Expiration in 2027 [Member] Investment Tax Credit Carryforward, Expiration in 2027 [Member] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Accumulated Deferred Investment Tax Credit Accumulated Deferred Investment Tax Credit Anticipated Decrease in unrecognized tax benefit during 12 months following current reporting date Anticipated Decrease in Unrecognized Tax Benefit During Twelve Months Following Current Reporting Date Anticipated decrease in unrecognized tax benefit during 12 months following current reporting date. Income Taxes (Textual) [Abstract] Income Taxes (Textual) [Abstract] Income taxes. Deferred Tax Assets, Net Reversal of liability for Unrecognized tax benefits Reversal of Liability for Unrecognized Tax Benefits Reversal of liability for Unrecognized tax benefits. Recognition of federal income tax benefit Recognition of Federal Income Tax Benefit Recognition of federal income tax benefit. Net Increase in valuation allowance recorded against net deferred tax assets Valuation Allowance, Deferred Tax Asset, Change in Amount Valuation allowance loss for the year Operating Loss Carryforwards, Valuation Allowance Period for Carry forward of tax benefits related to deferred tax assets Period for Carry Forward of Tax Benefits Related to Deferred Tax Assets Period for carry forward of tax benefits related to deferred tax assets. Deferred tax assets, operating loss carryforwards, federal Deferred Tax Assets, Operating Loss Carryforwards, Domestic Expiration year of federal NOL carryforward Operating Loss Carryforwards, Expiration Dates Deferred tax assets, operating loss carryforwards, state and local Deferred Tax Assets, Operating Loss Carryforwards, State and Local Minimum expiration period for state NOLs Minimum Expiration Period for State Net Operating Losses Minimum expiration period for state NOLs. Maximum expiration period for state NOLs Maximum Expiration Period for State Net Operating Losses Maximum expiration period for state NOLs. Deferred Tax Assets, Tax Credit Carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration Tax Credit Expiration Date Minimum Tax Credit Expiration Date Minimum Tax Credit Expiration Date Minimum Tax Credit Expiration Date Maximum Tax Credit Expiration Date Maximum Tax Credit Expiration Date Maximum Unrecognized tax benefits that if recognized would affect the Company's annual effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Total accrued interest and penalties related to unrecognized income tax benefits Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Uncertain tax positions Uncertain Tax Positions Uncertain tax positions. Goss unrecognized tax benefits Gross Unrecognized Tax Benefits Including Interest and Penalties Gross unrecognized tax benefits including interest and penalties. Income taxes refunded Proceeds from Income Tax Refunds Valuation allowance against net deferred tax assets Valuation Allowance, Amount Total deferred tax assets Goss unrecognized tax benefits Changes in the Company's warranty liability Movement in Standard Product Warranty Accrual [Roll Forward] Balance at beginning of year Warranties issued Standard Product Warranty Accrual, Warranties Issued Payments Standard Product Warranty Accrual, Payments Adjustments Product Warranty Accrual, Preexisting, Increase (Decrease) Balance at end of year Cash equivalents Cash Equivalents, at Carrying Value Collateral for LOC facilities included in restricted cash Estimated useful life for depreciation of property and equipment Property, Plant and Equipment, Useful Life Property and equipment amount Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Depreciation expense Advertising costs incurred Advertising Expense Expensed legal fees Legal Fees Loss Contingencies [Table] Loss Contingencies [Table] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Nevada Development Contract Litigation Nevada Development Contract Litigation [Member] Nevada development contract litigation. KB Home Coastal Inc. et al adv. Estancia Coastal Estancia Coastal Litigation [Member] Estancia Coastal Litigation Loss Contingencies [Line Items] Loss Contingencies [Line Items] Acres of purchased land by LVDA Area of Real Estate Property Expected compensatory damages Loss Contingency, Damages Sought, Value Loss Contingency, Range of Possible Loss, Minimum Loss Contingency, Range of Possible Loss, Minimum Court judgement in favor of plaintiff in the amount Litigation Settlement, Gross Pre-judgment interest to be paid in litigation settlement Litigation Settlement, Interest Expense Litigation Settlement, Interest Expense Additional legal accrual recorded Loss Contingency Accrual, Carrying Value, Period Increase (Decrease) Accrual for compensatory damage Loss Contingency, Accrual Carrying Value, Current Guarantor Subsidiaries 2011 Guarantor Subsidiaries 2011 [Member] Guarantor Subsidiaries 2011 [Member] Guarantor Subsidiaries 2010 Guarantor Subsidiaries 2010 [Member] Guarantor Subsidiaries 2010 [Member] Non-Guarantor Subsidiaries 2011 Non-Guarantor Subsidiaries 2011 [Member] Non-Guarantor Subsidiaries 2011 [Member] Non-Guarantor Subsidiaries 2010 Non-Guarantor Subsidiaries 2010 [Member] Non-Guarantor Subsidiaries 2010 [Member] Condensed Consolidated Statements of Cash Flows Adjustments to reconcile net loss to net cash provided (used) by operating activities: Equity in (income) loss of unconsolidated joint ventures Loss on loan guaranty Other, net Other Noncash Income (Expense) Return of investment in (contributions to) unconsolidated joint ventures Excess tax benefit associated with exercise of stock options Excess Benefit Associated with Exercise of Stock Options Excess benefit associated with the exercise of stock options. Intercompany Intercompany Transactions Intercompany transactions. Inventories Inventory, Operative Builders [Abstract] Homes under construction Inventory, Homes under Construction Land under development Inventory, Real Estate, Land and Land Development Costs Land held for future development Inventory, Land Held for Development and Sale Total Interest Costs Real Estate Inventory, Capitalized Interest Costs [Roll Forward] Capitalized interest at beginning of year Real Estate Inventory, Capitalized Interest Costs Capitalized interest related to consolidation of previously unconsolidated joint ventures Capitalized Interest Related to Consolidation of Previously Unconsolidated Joint Ventures Capitalized interest related to consolidation of previously unconsolidated joint ventures. Interest incurred Real Estate Inventory, Capitalized Interest Costs Incurred Interest expensed Interest Expense, Debt Interest amortized to construction and land costs Real Estate Inventory, Capitalized Interest Costs, Cost of Sales Capitalized interest at end of year Inventories (Textual) Inventories (Textual) [Abstract] Inventories. Gain (loss) on early extinguishment of debt Write-off of debt issuance costs Write off of Deferred Debt Issuance Cost Aggregate commitment under the credit facility Line of Credit Facility, Maximum Borrowing Capacity Financial Services Financial Services [Text Block] Financial services. Postretirement Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Supplemental Disclosure to Consolidated Statements of Cash Flows Cash Flow, Supplemental Disclosures [Text Block] Assets measured at fair value on a nonrecurring basis Fair Value Measurements, Nonrecurring [Table Text Block] Carrying values and estimated fair values of financial instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Schedule of Product Warranty Liability [Table Text Block] Schedule of Product Warranty Liability [Table Text Block] Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Variable Interest Entities Variable Interest Entities [Text Block] Variable interest entities. Summary of Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Stock option transactions Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Stock options outstanding and stock options exercisable Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block] Assumptions of Black-Scholes option-pricing model Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Restricted stock transactions Restricted Stock Transactions [Table Text Block] Restricted stock transactions. Preferred stock, par value Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Common stock, par value Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Grantor stock ownership trust Treasury stock, shares Jurisdiction for Lawsuit [Axis] Jurisdiction for Lawsuit [Axis] Jurisdiction for Lawsuit [Axis] Jurisdiction for Lawsuit [Domain] Jurisdiction for Lawsuit [Domain] [Domain] for Jurisdiction for Lawsuit [Axis] Florida State Court FLORIDA Louisiana Federal Court LOUISIANA Defective Drywall Material Damages from Product Defects [Member] Number of lawsuits in which company is a defendant Loss Contingency, Pending Claims, Number Number of omnibus class action lawsuits Loss Contingency, Pending Claims, Number of Class Action Lawsuits Loss Contingency, Pending Claims, Number of Class Action Lawsuits Commitments and Contingencies (Textual) [Abstract] Commitments and Contingencies (Textual) [Abstract] Commitments and contingencies. Structural warranty provided by the company Structural Warranty Provided by Company Structural warranty provided by the company. Minimum warranty on electrical and other building systems Minimum Warranty on Electrical Heating Cooling Plumbing and Other Building Systems Minimum warranty on electrical, heating, cooling, plumbing and other building systems Maximum warranty on electrical and other building systems Maximum Warranty on Electrical Heating Cooling Plumbing and Other Building Systems Maximum warranty on electrical, heating, cooling, plumbing and other building systems. Warranty for other components of a home Warranty for Other Components of Home Warranty for other components of a home. Company's warranty liability Warranty liability associated with defective drywall Warranty Liability Associated with Defective Drywall Warranty liability associated with defective drywall. Number of homes containing or suspected of containing defective drywall Number of Homes Containing or Suspected of Containing Defective Drywall Number of homes containing or suspected of containing defective drywall. Additional Number of affected homes associated with repair costs Additional Number of Affected Homes Associated with Repair Costs Additional Number of affected homes associated with repair costs. Payments made for the repair of homes containing defective drywall Payments Made for Repair of Homes Containing Defective Drywall Payments made for the repair of homes containing defective drywall. Payments made as repair costs for homes containing defective drywall Payments Made as Repair Costs for Homes Containing Defective Drywall Payments made as repair costs for homes containing defective drywall.