Acres of land related to land liens Acres of Land Related to Land Liens Acres of land related to land liens. Non-cash investing activities Supplemental Cash Flow Information [Abstract] Vested grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Net income (loss) attributable to common stockholders Net Income (Loss) Attributable to Parent Consolidated Entities [Axis] Consolidated Entities [Axis] Entity Emerging Growth Company Entity Emerging Growth Company Marketable securities - available-for-sale Debt Securities, Available-for-sale, Current Interest cost Defined Benefit Plan, Interest Cost Accumulated Depreciation Finite-Lived Intangible Assets, Accumulated Amortization Statistical Measurement [Domain] Statistical Measurement [Domain] Entity Address, Address Line One Entity Address, Address Line One Accrued long-term water assets included in current liabilities Accrued Long-term Water Assets Included in Current Liabilities Accrued Long-term Water Assets Included in Current Liabilities Additional paid-in capital Additional Paid in Capital, Common Stock Entity Filer Category Entity Filer Category Real estate development (includes $110,668 at September 30, 2021 and $108,600 at December 31, 2020, attributable to Centennial Founders, LLC, Note 15) Real estate development Inventory, Real Estate, Land and Land Development Costs Other assets Other Assets, Noncurrent Earnings (cost) components: Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [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] Investment, Name [Axis] Investment, Name [Axis] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Segments [Axis] Segments [Axis] Retirement Benefits [Abstract] Retirement Benefits [Abstract] (Decrease) increase in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cost of purchased water (per acre-foot) Cost of Purchased Water, Area Cost of Purchased Water, Area TRCC/Rock Outlet Center, LLC TRCC/Rock Outlet Center [Member] TRCC/Rock Outlet Center [Member] March 11, 2020 March 11, 2020 [Member] March 11, 2020 [Member] Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Current investment policy targets: Defined Benefit Plan, Plan Assets, Allocations [Abstract] Stock compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Summary of Available-for-Sale Securities Debt Securities, Available-for-sale [Table Text Block] Gain realized on sale Gain (Loss) on Disposition of Assets Document Fiscal Year Focus Document Fiscal Year Focus Accrued bonus Accrued Bonuses, Current TRC-MRC 3, LLC TRC-MRC 3 LLC [Member] TRC-MRC 3 LLC [Member] Receivables, inventories, prepaids and other assets, net Increase (Decrease) in Operating Assets Treasury/Corporate Notes Defined Benefit Plan, Debt Security [Member] Letter of credit renewal period Letter of Credit Renewal Period Letter of credit renewal period. Avek water for future delivery (in acre-feet) Long-term Water Assets, Water Contract Rights for Future Delivery (Volume) Long-term Water Assets, Water Contract Rights for Future Delivery (Volume) Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Water available for banking, sales, or internal use Transferable Water [Member] Transferable water. Accumulated other comprehensive loss OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Equity in Earnings (Loss) Equity In Earnings (Loss) Equity In Earnings (Loss) Award Type [Domain] Award Type [Domain] STOCK COMPENSATION - RESTRICTED STOCK AND PERFORMANCE SHARE GRANTS Stock Compensation Restricted Stock and Performance Share Grants [Text Block] Stock compensation restricted stock and performance share grants. Credit Facility [Domain] Credit Facility [Domain] ASSETS Assets [Abstract] Related Party Transactions [Abstract] Related Party Transactions [Abstract] Other Liabilities Other Liabilities [Abstract] Net amortization and deferral Defined Benefit Plan, Amortization of Gain (Loss) Land Land [Member] Other Liabilities Other Liabilities [Member] Total water held for future use Long-term Water Assets, Banked Water and Water Contract Rights (Volume) Long-term Water Assets, Banked Water and Water Contract Rights (Volume) INTEREST RATE SWAP Derivative Instruments and Hedging Activities Disclosure [Text Block] Summary of Maturities, at Par, of Marketable Securities by Year Investments Classified by Contractual Maturity Date [Table Text Block] New stock grants/additional shares due to maximum achievement (in shares) Shares granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Deficit balance Distributions in Excess of Investment in Unconsolidated Joint Venture Distributions in Excess of Investment in Unconsolidated Joint Venture Entity Address, City or Town Entity Address, City or Town Additional reimbursement funds Additional Reimbursement Funds Additional reimbursement funds. Fair Value Derivative Assets (Liabilities), at Fair Value, Net Retained Earnings Retained Earnings [Member] Assumptions used in determining periodic pension cost: Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Consolidated joint venture, ownership interest Noncontrolling Interest, Ownership Percentage by Parent East CFD East Community Facilities Districts [Member] -- None. No documentation exists for this element. -- Other Liabilities Disclosure [Abstract] Other Liabilities Disclosure [Abstract] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Related Party [Axis] Related Party [Axis] Schedule of Components of Water Assets Disclosure of Long Lived Assets Held-for-sale [Table Text Block] Distribution of earnings from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution March 18 2021 March 18, 2021 [Member] March 18 2021 Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Shares withheld for taxes and tax benefit of vested shares (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Capitalized Share-based Payment Arrangement, Amount Capitalized Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Non-cash retirement plan (benefit) expense Pension and Other Postretirement Benefits Cost (Reversal of Cost) Long-term water assets (in acre-feet) Long-term Water Assets (Volume) Long-term Water Assets (Volume) Entity Interactive Data Current Entity Interactive Data Current Payments to Acquire Real Estate and Real Estate Joint Ventures Payments to Acquire Real Estate and Real Estate Joint Ventures Other comprehensive gain (loss) before taxes Other Comprehensive Income (Loss), before Tax Weighted Average Interest Pay Rate Derivative, Fixed Interest Rate Net income (loss) per share attributable to common stockholders, basic (in dollars per share) Earnings Per Share, Basic TRC-MRC 2, LLC TRC-MRC 2 LLC [Member] TRC-MRC 2 LLC [Member] Stock grants outstanding beginning of the year at target achievement (in shares) Stock grants outstanding end of the year at target achievement (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Document Type Document Type 18-19 West, LLC Eighteen Nineteen West Llc [Member] Eighteen nineteen west llc. WRMWSD - Contracts with the Company Wheeler Ridge Maricopa Water Storage District Wheeler Ridge Maricopa Water Storage District [Member] Wheeler Ridge Maricopa Water Storage District [Member] Debt Debt Borrowings Borrowings Maximum performance (in shares) Performance Awards Granted with Performance Conditions, Maximum Number of Shares to be Issued, at Maximum Performance Performance Awards Granted with Performance Conditions, Maximum Number of Shares to be Issued, at Maximum Performance Service period Defined Benefit Plan, Average Service Period Defined Benefit Plan, Average Service Period Summary of stock grant activity: Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Entity Current Reporting Status Entity Current Reporting Status Summary of Stock Grant Activity Schedule of Nonvested Share Activity [Table Text Block] Shares withheld for taxes and tax benefit of vested shares Share-based Payment Arrangement, Decrease for Tax Withholding Obligation Number of parties in agreement for settlement Loss Contingency, Number of Plaintiffs Water held for future use Antelope Valley East Kern Water Agency [Member] Antelope valley east kern water agency. Target performance (in shares) Performance Awards Granted with Performance Conditions, Number of Shares to be Issued, at Target Performance Performance Awards Granted with Performance Conditions, Number of Shares to be Issued, at Target Performance Long Lived Assets Held-for-sale, Name [Domain] Long Lived Assets Held-for-sale, Name [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Plan Name [Axis] Plan Name [Axis] Distribution of equity from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution, Return of Capital Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Document Transition Report Document Transition Report Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Accrued capital expenditures included in current liabilities Change In Capital Expenditures Incurred But Not Yet Paid Change In Capital Expenditures Incurred But Not Yet Paid Tejon Ranch Commerce Center Inventory, Real Estate, Improvements, Gross Inventory, Real Estate, Improvements, Gross Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] TOTAL LIABILITIES AND EQUITY Liabilities and Equity Annual fee increase Long Term Water Assets, Purchased, Annual Fee Increase, Percent Long Term Water Assets, Purchased, Annual Fee Increase, Percent Accrued liabilities and other Accrued liabilities and other Other Accrued Liabilities, Current Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Deferred income Contract with Customer, Liability, Current Scenario [Axis] Scenario [Axis] Restricted cash (Shown in Other Assets) Restricted Cash Number of acres for development Contribution for Joint Venture for Future Development Contribution for joint venture for future development. Revenues Revenue from Purchased Water Revenue from Purchased Water LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Interest Rate Swap Interest Rate Swap [Member] Current liabilities Increase (Decrease) in Operating Liabilities BASIS OF PRESENTATION Business Description and Basis of Presentation [Text Block] Unconsolidated joint ventures, ownership interest Equity Method Investment, Ownership Percentage Company water bank Long-term Water Assets, Banked Water Held at Company Owned Water Bank (Volume) Long-term Water Assets, Banked Water Held at Company Owned Water Bank (Volume) Standby letter of credit Standby Letters of Credit [Member] Schedule of Real Estate Schedule of Real Estate Properties [Table Text Block] Grapevine Grapevine [Member] Grapevine [Member] Profit margin Earnings (Loss) Gross Profit Bond debt sold by TRPFFA Long-term Line of Credit U.S. Treasury and agency notes U.S. Treasury and agency notes US Treasury and Government Short-term Debt Securities [Member] Balance Sheet Location [Domain] Balance Sheet Location [Domain] SWP Water Contracts State Water Project Contracts [Member] State water project contracts. Comprehensive income (loss) attributable to non-controlling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Financial obligation fulfilled Lessee, Operating Lease, Liability, Paid Lessee, Operating Lease, Liability, Paid (Loss) income from operations before equity in earnings of unconsolidated joint ventures Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Less: deferred loan costs Annual cost related to the letter of credit Debt Issuance Costs, Net Dudley-Ridge water rights Dudley Ridge Water Rights [Member] Dudley Ridge Water Rights [Member] Ranchcorp Subsidiaries [Member] Marketable Securities, with unrealized gains Gross unrealized holding gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Schedule Of Equity Method Investment Equity Method Investee Name Axis [Domain] Schedule Of Equity Method Investment Equity Method Investee Name Axis [Domain] Schedule Of Equity Method Investment Equity Method Investee Name Axis [Domain] Trading Symbol Trading Symbol Current Liabilities: Liabilities, Current [Abstract] Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Total Stock Compensation Costs Share-based Payment Arrangement, Accelerated Cost LINE OF CREDIT AND LONG-TERM DEBT Debt Disclosure [Text Block] Beginning balance (in shares) Ending balance (in shares) Shares, Outstanding Restricted stock issuance Stock Issued During Period, Value, Restricted Stock Award, Gross PEF Pastoria Energy Facility, LLC [Member] Pastoria Energy Facility, LLC [Member] SERP Supplemental Employee Retirement Plan [Member] Accounting Policies [Abstract] Accounting Policies [Abstract] TRCC-East TRCC-East [Member] TRCC-East [Member] Contractual obligation for future water payments Contractual Obligation Derivative Instrument [Axis] Derivative Instrument [Axis] Number of reportable segments Number of Reportable Segments Petro Travel Plaza Holdings, LLC Petro Travel Holdings Llc Plaza [Member] Petro travel holdings llc plaza. Letters of credit outstanding amount Letters of Credit Outstanding, Amount Debt Securities, Available for Sale Securities, Fair Market Value Exceeds Cost Basis, by Amount Debt Securities, Available for Sale Securities, Fair Market Value Exceeds Cost Basis, by Amount Debt Securities, Available for sale securities, fair market value exceeds cost basis, by amount. Schedule of Components of Segment Revenues Revenue from External Customers by Products and Services [Table Text Block] Corporate notes Corporate notes Corporate Note Securities [Member] Percentage of current water usage with the adjudication boundary (more than) Loss Contingency, Settlement, Percent of Water Use Within the Adjudication Boundary Loss Contingency, Settlement, Percent of Water Use Within the Adjudication Boundary Issued and outstanding shares - 26,352,193 at September 30, 2021 and 26,276,830 at December 31, 2020 Common Stock, Value, Issued Total other income Nonoperating Income (Expense) Total compensation cost not yet recognized, period for recognition Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Performance share grants Performance Shares [Member] Contribution to unconsolidated joint venture Value of property contributed Contribution of Property Commitments and contingencies Commitments and Contingencies Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Schedule of Interest Rate Derivatives Schedule of Interest Rate Derivatives [Table Text Block] Reconciliation to amounts on consolidated balance sheets: Cash and Cash Equivalents, at Carrying Value [Abstract] Ownership [Axis] Ownership [Axis] Document Period End Date Document Period End Date MARKETABLE SECURITIES Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Common stock equivalents (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Total expenses Segment losses Costs and Expenses Total water held for future use and purchased water contracts Long Term Water Assets, Contracts with Company Long Term Water Assets, Contracts with Company Entity Registrant Name Entity Registrant Name Pension and supplemental executive retirement plan liability Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent Ranch operations Ranch Operations [Member] Ranch Operations [Member] Estimated tax of change in value of available-for-sale securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Schedule of Other Liabilities Other Liabilities [Table Text Block] Financial Instrument [Axis] Financial Instrument [Axis] Fair Value Debt Securities, Available-for-Sale, Excluding Accrued Interest Total revenues Commercial/industrial revenues Revenue from Contract with Customer, Excluding Assessed Tax Accrued vacation Accrued Vacation, Current Investment in unconsolidated joint ventures Payments to Acquire Interest in Joint Venture Cost Reported Value Measurement [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Common Stock Shares Outstanding Common Stock [Member] Five West Parcel, LLC Five West Parcel Llc [Member] Five west parcel llc. REPORTING SEGMENTS AND RELATED INFORMATION Segment Reporting Disclosure [Text Block] Operating (loss) income Operating results Operating Income (Loss) Long Lived Assets Held-for-sale by Asset Type [Axis] Long Lived Assets Held-for-sale by Asset Type [Axis] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Summary of Performance Share Grants with Performance Conditions Schedule of Share-based Payment Award, Performance Share Awards Granted, by Performance Conditions [Table Text Block] Schedule of Share-based Payment Award, Performance Share Awards Granted, by Performance Conditions [Table Text Block] Gross unrealized holding losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Stock compensation expense Share-based Payment Arrangement, Noncash Expense Investments in water assets Payments to Acquire Other Investments Additional Paid-In Capital Additional Paid-in Capital [Member] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Schedule Of Equity Method Investment Equity Method Investee Name Axis [Axis] Schedule Of Equity Method Investment Equity Method Investee Name Axis [Axis] Schedule Of Equity Method Investment Equity Method Investee Name Axis TRC-MRC 1, LLC TRC-MRC 1 LLC [Member] TRC-MRC 1 LLC [Member] Water contracts and related costs Related Party Transaction, Amounts of Transaction Real estate - resort/residential Resort and Residential Real Estate [Member] Resort and Residential Real Estate [Member] Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Axis] DMB DMB Pacific LLC [Member] DMB Pacific LLC [Member] Notional Amount Derivative, Notional Amount Other income, net Other Nonoperating Income (Expense) Number of directors Number of Directors Number of Directors Real estate and equipment expenditures Payments to Acquire Property, Plant, and Equipment Mountain Village Tejon Mountain Village Llc [Member] Tejon mountain village llc. OTHER LIABILITIES Other Liabilities Disclosure [Text Block] Maximum Maximum [Member] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Total liabilities Liabilities Legal Entity [Axis] Legal Entity [Axis] Schedule of Accrued Liabilities and Other Schedule of Accrued Liabilities [Table Text Block] Award Type [Axis] Award Type [Axis] Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Total water held for future use at cost Total cost water held for future use Tangible Water Assets, Banked Water and Water Contract Rights Tangible Water Assets, Banked Water and Water Contract Rights Equity method investment, deferred gain on sale Equity Method Investment, Deferred Gain on Sale Total Tejon Ranch Co. Stockholders’ Equity Stockholders' Equity Attributable to Parent Consolidation Items [Axis] Consolidation Items [Axis] Settled Litigation Settled Litigation [Member] Common stock, issued shares (in shares) Common Stock, Shares, Issued Incentive fee on contract termination, measurement period from entitlement achievement date Contract Termination, Incentive Fee Calculation, Measurement Period From Entitlement Achievement Date Contract Termination, Incentive Fee Calculation, Measurement Period From Entitlement Achievement Date Real estate - commercial/industrial Commercial and Industrial [Member] Commercial and industrial. INVESTMENT IN UNCONSOLIDATED AND CONSOLIDATED JOINT VENTURES Equity Method Investments and Joint Ventures Disclosure [Text Block] Banked water and water for future delivery Banked Water and Water for Future Delivery [Member] Banked water and water for future delivery. Mineral resources Mineral Resources [Member] Mineral Resources [Member] Executive Vice President and Chief Operating Officer Management [Member] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] TRC-MRC 4 LLC TRC-MRC 4 LLC [Member] TRC-MRC 4 LLC Tejon Ranch Co. Stockholders’ Equity Stockholders' Equity Attributable to Parent [Abstract] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Investment income Investment Income, Net Additional bond debt authorized to be sold in future Debt instrument face amount Debt Instrument, Face Amount Expected long-term rate of return on plan assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Total net periodic pension earnings Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Letter of credit period Letter of credit period Letter of credit period. City Area Code City Area Code Retained earnings Retained Earnings (Accumulated Deficit) Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Litigation Case [Domain] Litigation Case [Domain] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Property tax payable Accrual for Taxes Other than Income Taxes, Current Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Majestic Realty Co. Majestic Realty Co. [Member] Majestic Realty Co. [Member] Other Other Employee-related Liabilities, Current Commercial/industrial revenues and equity in earnings of unconsolidated joint ventures Revenues and Income (Loss) from Equity Method Investments Revenues and Income (Loss) from Equity Method Investments Equities Defined Benefit Plan, Equity Securities [Member] Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Investment in unconsolidated joint ventures TRC equity Equity Method Investments Statement of Operations Income Statement [Abstract] Amendment Flag Amendment Flag 1998 Plan Stock Incentive Plan 1998 [Member] Stock incentive plan. Summary of Assumptions Used to Determine The Price of Market-Based Performance Condition Grants Schedule of Share-based Payment Award, Equity Instruments Other than Options, Valuation Assumptions [Table Text Block] Schedule of Share-based Payment Award, Equity Instruments Other than Options, Valuation Assumptions [Table Text Block] Fair Value Estimate of Fair Value Measurement [Member] Schedule of Water Revenues and Cost of Sales Schedule of Water Revenues and Cost of Sales [Table Text Block] Schedule of Water Revenues and Cost of Sales [Table Text Block] Simulated monte carlo share price (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Simulated Price Share-based Compensation Arrangement by Share-based Payment Award, Simulated Price Area of building owned and leased Lease of Building Lease of building. Related Party Transaction [Axis] Related Party Transaction [Axis] Restricted stock issuance (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Total equity Beginning balance, value Ending balance, value Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Income tax (benefit) expense Income Tax Expense (Benefit) Accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Equity Components [Axis] Equity Components [Axis] Number of tenants Joint Venture, Number of Tenants Joint Venture, Number of Tenants Total current assets Assets, Current Estimated future payments Lessee, Operating Lease, Liability, to be Paid Current investment mix Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Expired/forfeited grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Inventories Inventory, Net Non-cash write-off of leasing assets Non-cash Write-off of Tenant Receivables Non-cash Write-off of Tenant Receivables Entity File Number Entity File Number Equity Method Investment, Nonconsolidated Investee [Domain] Equity Method Investment, Nonconsolidated Investee [Domain] Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures [Abstract] Balance Sheet Information Statement of Financial Position [Abstract] Threshold performance (in shares) Performance Awards Granted with Performance Conditions, Minimum Number of Shares to be Issued, at Threshold Performance Performance Awards Granted with Performance Conditions, Minimum Number of Shares to be Issued, at Threshold Performance Number of acres for development Development of Building Development of building. Less: line-of-credit and current maturities of long-term debt Long-term Debt, Current Maturities Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Schedule of Weighted Average Number of Shares Outstanding Schedule of Weighted Average Number of Shares [Table Text Block] Entity Small Business Entity Small Business Proceeds from sale of real estate/assets Proceeds from Sale of Real Estate Held-for-investment Equity Component [Domain] Equity Component [Domain] Contract-based intangible assets Contract-Based Intangible Assets [Member] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Schedule of Condensed Statements of Operations and Balance Sheet Information of Consolidated and Unconsolidated Joint Ventures Schedule of Condensed Income Statement and Balance Sheet Related to Joint Ventures [Table Text Block] Schedule of condensed income statement and balance sheet related to joint ventures. Long Lived Assets Held-for-sale [Line Items] Long Lived Assets Held-for-sale [Line Items] Statement [Line Items] Statement [Line Items] Litigation Case [Axis] Litigation Case [Axis] Gain on sale of property plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Retirement Plan Type [Domain] Retirement Plan Type [Domain] Summary of Stock Compensation Costs for Employee and NDSI Plans Share-based Payment Arrangement, Cost by Plan [Table Text Block] Counterparty Name [Domain] Counterparty Name [Domain] Non-cash tenant allowance amortization Equity Method Investment, Summarized Financial Information, Amortization Of Tenant Allowances Equity Method Investment, Summarized Financial Information, Amortization Of Tenant Allowances Debt Disclosure [Abstract] Debt Disclosure [Abstract] Entity Address, State or Province Entity Address, State or Province Funds invested in marketable securities Payments to Acquire Marketable Securities Income before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Level 2 Fair Value, Inputs, Level 2 [Member] Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Axis] Long-term deferred gains Contract with Customer, Liability, Noncurrent Farming Farming and Agriculture [Member] Farming and agriculture. Corporate expenses Corporate, Non-Segment [Member] Segment Reporting [Abstract] Segment Reporting [Abstract] Entity [Domain] Entity [Domain] Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Schedule of Tangible Water Assets Tangible Water Assets [Table Text Block] Tangible Water Assets [Table Text Block] Building and Land Land and Building [Member] RETIREMENT PLANS Retirement Benefits [Text Block] Entity Shell Company Entity Shell Company Local Phone Number Local Phone Number Forecast Forecast [Member] Acres of land Related Party Transaction, Area of Land Related Party Transaction, Area of Land TOTAL ASSETS Assets Assets (Expense) benefit for income taxes related to other comprehensive income items Other Comprehensive Income (Loss), Tax Investment, Name [Domain] Investment, Name [Domain] Plan Name [Domain] Plan Name [Domain] Common stock, authorized shares (in shares) Common Stock, Shares Authorized Noncontrolling Interest Noncontrolling Interest [Member] Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Tulare Lake Basin water rights Tulare Lake Basin Water Rights [Member] Tulare Lake Basin Water Rights [Member] Derivative Contract [Domain] Derivative Contract [Domain] Net income (loss) attributable to non-controlling interest Net Income (Loss) Attributable to Noncontrolling Interest Centennial Centennial Founders LLC [Member] Centennial Founders LLC Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Equity Method Investment, Nonconsolidated Investee or Group of Investees Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] Net cash (used in) provided by operating activities Net Cash Provided by (Used in) Operating Activities (Loss) gain on sale of real estate Gains (Losses) on Sales of Investment Real Estate Litigation Status [Axis] Litigation Status [Axis] West CFD West Community Facilities Districts [Member] West community facilities districts. Schedule of Components of Long-term Debt Schedule of Debt [Table Text Block] Net investment in water assets Net investments in water assets Long Term Assets Held for Future Use or Sale Long term assets held for future use or sale. Entity Tax Identification Number Entity Tax Identification Number Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Common stock (in shares) Weighted Average Number of Shares Outstanding, Basic Net income (loss) per share attributable to common stockholders, diluted (in dollars per share) Earnings Per Share, Diluted Segments [Domain] Segments [Domain] Total Debt Securities, Available for Sale Securities, Excluding Accrued Interest, Maturities at Par Debt Securities, Available for sale securities maturities, at par. Less accumulated depreciation Inventory, Real Estate, Improvements, Accumulated Depreciation Inventory, Real Estate, Improvements, Accumulated Depreciation Investments in unconsolidated joint ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Share price at target achievement (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Price at Target Achievement Share-based Compensation Arrangement by Share-based Payment Award, Price at Target Achievement Acre-Feet Sold Long Term Water Assets, Water Sold (Volume) Long Term Water Assets, Water Sold (Volume) Comprehensive income (loss) attributable to common stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Summary of maturities, at par, of marketable securities Available For Sale Debt Securities, Fiscal Year Maturity [Abstract] Available for sale debt securities, fiscal year maturity. Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Other comprehensive gain (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] KCWA Kern County Water Agency [Member] Kern County Water Agency [Member] Weighted average number of shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Deferred tax liability Deferred Income Tax Liabilities, Net Related Party Transaction [Line Items] Related Party Transaction [Line Items] Reimbursement proceeds from Community Facilities District Payments for (Proceeds from) Other Investing Activities, Business Three Payments for (Proceeds from) Other Investing Activities, Business Three Equity in earnings of unconsolidated joint ventures, net Equity in earnings of unconsolidated joint ventures, net Equity in earnings (loss) Income (Loss) from Equity Method Investments Interest rate swap liability Derivative Liability, Noncurrent Notes payable Notes Payable Non-cash profits recognized from land contribution Gain (Loss) on Disposition of Other Assets Water held for future use Long-term Water Assets, Banked Water and Water Contract Rights [Abstract] Long-term Water Assets, Banked Water and Water Contract Rights [Abstract] Tejon-Castac Water District Tejon-Castac Water District [Member] Tejon-Castac Water District [Member] Trade accounts payable Accounts Payable, Current Total Stockholders' Equity Parent [Member] Depreciation and amortization Depreciation, Depletion and Amortization Additional costs for future years Additional Reimbursement Funds, Costs Reserved For Future Years Additional Reimbursement Funds, Costs Reserved For Future Years Total cost of land Contribution of Property, Transaction Costs Contribution of Property, Transaction Costs Accumulated Other Comprehensive (Loss) Income AOCI Attributable to Parent [Member] Number of types of stock grant awards Share Based Compensation Arrangement by Share Based Payment Award, Number of Award Types Share Based Compensation Arrangement by Share Based Payment Award, Number of Award Types Common stock, outstanding shares (in shares) Common Stock, Shares, Outstanding Financial Instruments [Domain] Financial Instruments [Domain] Unrealized gain (loss) on interest rate swap Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Revenues: Revenues [Abstract] Contributions to defined benefit plan Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year Excess joint venture distributions and other Other Sundry Liabilities, Noncurrent Right and share of profit and loss Equity Method Investment, Right and Share of Income and (Loss) Equity Method Investment, Right and Share of Income and (Loss) Income taxes receivable Income Taxes Receivable Construction Loan Equity Method Investment Summarized Financial Information, Line of Credit Facility, Maximum Borrowing Capacity Equity Method Investment Summarized Financial Information, Line of Credit Facility, Maximum Borrowing Capacity Contract renewal optional term Long Term Water Assets, Contract Renewal Optional Term Long Term Water Assets, Contract Renewal Optional Term Long-term Water Assets [Line Items] Long-term Water Assets [Line Items] Long-term Water Assets [Line Items] Consolidated Entities [Domain] Consolidated Entities [Domain] Proceeds from water sales Proceeds from sale of other investments Proceeds from Sale of Other Investments Annual option payment Long Term Water Assets, Purchased, Annual Option Payment, Percent Long Term Water Assets, Purchased, Annual Option Payment, Percent Award Date [Domain] Award Date [Domain] Accrued interest receivable balance Accrued Investment Income Receivable Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Excess tax shortfall from stock-based compensation Deferred Tax Expense from Stock Options Exercised Loss Contingencies [Line Items] Loss Contingencies [Line Items] Property and equipment, net Property, Plant and Equipment, Net LONG-TERM WATER ASSETS Property, Plant and Equipment Disclosure [Text Block] Other liabilities Total Other Liabilities, Noncurrent Profit Gross Profit from Purchased Water Gross Profit from Purchased Water Number of community facility districts Number of Community Facility Districts Number of Community Facility Districts Repayments of long-term debt Repayments of Long-term Debt Schedule of Long Lived Assets Held-for-sale [Table] Schedule of Long Lived Assets Held-for-sale [Table] Profit from water sales Profit from water sales Gain (Loss) on Sale of Other Investments ACCRUED LIABILITIES AND OTHER Accounts Payable and Accrued Liabilities Disclosure [Text Block] Related Party Transaction [Domain] Related Party Transaction [Domain] Document Quarterly Report Document Quarterly Report Revenues Revenues Operating results from commercial/industrial and unconsolidated joint ventures Operating Income (Loss), Including Equity In Earnings Of Unconsolidated Joint Ventures Operating Income (Loss), Including Equity In Earnings Of Unconsolidated Joint Ventures Entity Common Stock Shares Outstanding Entity Common Stock, Shares Outstanding Costs and Expenses: Costs and Expenses [Abstract] Long-term debt, less current portion Long-term Debt, Excluding Current Maturities Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Total fair value of award Stock compensation costs, expensed Share-based Payment Arrangement, Expense Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Document Fiscal Period Focus Document Fiscal Period Focus Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Net income (loss) Net income (loss) Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Current maturities of long-term debt Debt, Current Amortization of premium/discount of marketable securities Accretion (Amortization) of Discounts and Premiums, Investments Long-term Debt, Current and Noncurrent [Abstract] Long-term Debt, Current and Noncurrent [Abstract] Counterparty Name [Axis] Counterparty Name [Axis] Maturities and sales of marketable securities Proceeds from Sale and Maturity of Marketable Securities Payables and Accruals [Abstract] Payables and Accruals [Abstract] Cash, cash equivalents, and restricted cash at beginning of period Cash, cash equivalents, and restricted cash at end of period Total cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Common stock, par value per share (in dollars per share) Common Stock, Par or Stated Value Per Share Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] 2021 Debt Securities, Available for Sale Securities, Excluding Accrued Interest, Maturities Year One at Par Debt Securities, Available for sale securities maturities, year one, at par. Current Assets: Assets, Current [Abstract] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Taxes on vested stock grants Proceeds from (Payments for) Other Financing Activities Costs Finite-Lived Intangible Assets, Gross Award Date [Axis] Award Date [Axis] Entity Central Index Key Entity Central Index Key Schedule of Finite-Lived Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Security Exchange Name Security Exchange Name Unrealized loss on available-for-sale securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment and Tax Purchased water contracts Related Party Transaction, Long-term Water Assets, Water Contracts (Volume) Related Party Transaction, Long-term Water Assets, Water Contracts (Volume) Nickel water rights Nickel Water Rights [Member] Nickel Water Rights [Member] Diluted shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Real estate and improvements - held for lease, net Real estate and improvements - held for lease, net Inventory, Real Estate, Improvements Other comprehensive gain (loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax INCOME TAXES Income Tax Disclosure [Text Block] Related Party [Domain] Related Party [Domain] Current Fiscal Year End Date Current Fiscal Year End Date Real Estate [Abstract] Real Estate [Abstract] EQUITY Stockholders' Equity Note Disclosure [Text Block] Schedule of Components of Net Periodic Pension Cost Schedule of Net Benefit Costs [Table Text Block] Measurement Basis [Axis] Measurement Basis [Axis] Acres of land transferred Acres of Land Transferred Acres of Land Transferred Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Other Income: Nonoperating Income (Expense) [Abstract] Name of Property [Axis] Name of Property [Axis] Credit Facility [Axis] Credit Facility [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Net cash (used in) provided by investing activities Net Cash Provided by (Used in) Investing Activities Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Cost of sales Cost of Purchased Water Long term deferred profit on land contribution Deferred Gain On Contribution Of Land Deferred Gain On Contribution Of Land Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Decrease in outstanding amount Debt Instrument, Increase (Decrease), Net Amount expected to be paid Purchase Commitment, Remaining Minimum Amount Committed Total current liabilities Liabilities, Current December 12, 2019 December 12, 2019 [Member] December 12, 2019 [Member] Tejon Ranch Commerce Center Tejon Ranch Commerce Center [Member] Tejon Ranch Commerce Center [Member] Litigation Status [Domain] Litigation Status [Domain] Money market funds Money Market Funds [Member] Loss Contingencies [Table] Loss Contingencies [Table] Accrued paid personal leave Accrued Paid Personal Leave, Current Accrued Paid Personal Leave, Current Ownership [Domain] Ownership [Domain] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Special taxes paid Taxes, Other Antelope Valley Groundwater Cases Antelope Valley Groundwater Cases [Member] Antelope Valley Groundwater Cases [Member] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Net income Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Title of 12(b) Security Title of 12(b) Security Statement [Table] Statement [Table] Purchased water contracts Long-term Water Assets, Water Contracts (Volume) Long-term Water Assets, Water Contracts (Volume) Water assets, volume available for purchase from 2017-2030 (up to) (in acre-feet) Long-term Water Assets (Volume), Amount After Year One Long-term Water Assets (Volume), Amount After Year One Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Rockefeller Joint Ventures Rockefeller Joint Ventures [Member] Rockefeller joint ventures. Total compensation cost not yet recognized Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Statistical Measurement [Axis] Statistical Measurement [Axis] REAL ESTATE Real Estate Disclosure [Text Block] NDSI Plan Non-Employee Director Stock Incentive Plan [Member] Non-employee director stock incentive plan. Construction loan Construction Loan Cover [Abstract] Cover [Abstract] Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Net cost of purchased water contracts Finite-Lived Intangible Assets, Net Water available for banking, sales, or internal use Long-term Water Assets, Transferrable Water (Volume) Long-term Water Assets, Transferrable Water (Volume) 2022 Debt Securities, Available for Sale Securities, Excluding Accrued Interest, Maturities, Year Two, at Par Debt Securities, Available for sale securities maturities, year two, at par. Non-controlling interest Stockholders' Equity Attributable to Noncontrolling Interest December 11 2020 December 11, 2020 [Member] December 11, 2020 Marketable Securities, with unrealized losses for less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Name of Property [Domain] Name of Property [Domain] Total purchased water contracts Long-term Water Assets, Intangible Water Contracts (Volume) Long-term Water Assets, Intangible Water Contracts (Volume) Scenario [Domain] Scenario [Domain] Adjustments to reconcile net income (loss) to net cash used by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Pension plan Pension Plan [Member] RELATED PARTY TRANSACTIONS Related Party Transactions Disclosure [Text Block] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Deferred income taxes Deferred Income Tax Expense (Benefit) Lease agreement, rentable space Joint Venture, Percentage of Rentable Space Occupied Joint Venture, Percentage of Rentable Space Occupied Number of joint venture contracts Number of Joint Venture Contracts Number of joint venture contracts.