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 Acres of land related to land liens Acres of Land Related to Land Liens Acres of land related to land liens. Document Type Document Type Other income, net Other Nonoperating Income (Expense) Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Related Party [Axis] Related Party [Axis] Payables and Accruals [Abstract] Payables and Accruals [Abstract] Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Segments [Axis] Segments [Axis] Retirement Plans Retirement Benefits [Text Block] 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 Maturities and sales of marketable securities Proceeds from Sale and Maturity of Marketable Securities Contractual obligation for future water payments Contractual Obligation Statistical Measurement [Domain] Statistical Measurement [Domain] LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Deferred tax liability Deferred Income Tax Liabilities, Net Interest Rate Swap Derivative Instruments and Hedging Activities Disclosure [Text Block] Security Exchange Name Security Exchange Name Operating loss Operating Income (Loss) 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] Total current liabilities Liabilities, Current Performance share grants Performance Shares [Member] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Commitments and contingencies Commitments and Contingencies Shares withheld for taxes and tax benefit of vested shares Share-based Payment Arrangement, Decrease for Tax Withholding Obligation ASSETS Assets [Abstract] TRC-MRC 3, LLC TRC-MRC 3 LLC [Member] TRC-MRC 3 LLC [Member] Investment, Name [Axis] Investment, Name [Axis] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Accounting Policies [Abstract] Accounting Policies [Abstract] Ranchcorp Subsidiaries [Member] Entity Address, State or Province Entity Address, State or Province Vested grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Payments for water contracts Operating Lease, Payments Trade accounts payable Accounts Payable, Current Other comprehensive gain (loss) before taxes Other Comprehensive Income (Loss), before Tax Letter of credit renewal period Letter of Credit Renewal Period Letter of credit renewal period. Accrued Liabilities and Other Accounts Payable and Accrued Liabilities Disclosure [Text Block] Retained earnings Retained Earnings (Accumulated Deficit) Reconciliation to amounts on consolidated balance sheets: Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] 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) Water available for banking, sales, or internal use Transferable Water [Member] Transferable water. Investment in unconsolidated joint ventures Payments to Acquire Interest in Joint Venture Equity in Earnings (Loss) Equity In Earnings (Loss) Equity In Earnings (Loss) Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Total compensation cost not yet recognized Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount 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. Long Lived Assets Held-for-sale [Line Items] Long Lived Assets Held-for-sale [Line Items] Real estate development (includes $108,976 at March 31, 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 Beginning balance (in shares) Ending balance (in shares) Shares, Outstanding 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) Other comprehensive gain (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Deficit balance Distributions in Excess of Investment in Unconsolidated Joint Venture Distributions in Excess of Investment in Unconsolidated Joint Venture Common stock, par value per share (in dollars per share) Common Stock, Par or Stated Value Per Share Other liabilities Total Other Liabilities, Noncurrent Additional reimbursement funds Additional Reimbursement Funds Additional reimbursement funds. Other Liabilities Other Liabilities [Abstract] Stock compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Water contracts and related costs Related Party Transaction, Amounts of Transaction East CFD East Community Facilities Districts [Member] -- None. No documentation exists for this element. -- Inventories Inventory, Net Total revenues Revenue from Contract with Customer, Excluding Assessed Tax Contributions to defined benefit plan Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Statement [Line Items] Statement [Line Items] Forecast Forecast [Member] March 18 2021 March 18, 2021 [Member] March 18 2021 Long-term water assets (in acre-feet) Long-term Water Assets (Volume) Long-term Water Assets (Volume) Statement [Table] Statement [Table] Interest cost Defined Benefit Plan, Interest Cost Statistical Measurement [Axis] Statistical Measurement [Axis] Credit Facility [Axis] Credit Facility [Axis] Interest rate swap liability Derivative Liability, Noncurrent Schedule of weighted average number of shares outstanding Schedule of Weighted Average Number of Shares [Table Text Block] TRC-MRC 2, LLC TRC-MRC 2 LLC [Member] TRC-MRC 2 LLC [Member] 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] Entity Small Business Entity Small Business 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 Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Line of Credit and Long-Term Debt Debt Disclosure [Text Block] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Amendment Flag Amendment Flag 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 Weighted average number of shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Purchase of assets Investment in Joint Venture Purchase Price Increase Amount Investment in Joint Venture Purchase Price Increase Amount Corporate expenses Corporate, Non-Segment [Member] Accrued liabilities and other Total Other Accrued Liabilities, Current Bond debt sold by TRPFFA Long-term Line of Credit Amount expected to be paid Purchase Commitment, Remaining Minimum Amount Committed Current investment policy targets: Defined Benefit Plan, Plan Assets, Allocations [Abstract] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Entity Central Index Key Entity Central Index Key Related Party [Domain] Related Party [Domain] Long Lived Assets Held-for-sale, Name [Domain] Long Lived Assets Held-for-sale, Name [Domain] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Marketable securities - available-for-sale Debt Securities, Available-for-sale, Current Derivative Instrument [Axis] Derivative Instrument [Axis] 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 Financial Instruments [Domain] Financial Instruments [Domain] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Schedule of finite-lived intangible assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Annual fee increase Long Term Water Assets, Purchased, Annual Fee Increase, Percent Long Term Water Assets, Purchased, Annual Fee Increase, Percent Standby letter of credit Standby Letters of Credit [Member] Executive Vice President and Chief Operating Officer Management [Member] Number of acres for development Contribution for Joint Venture for Future Development Contribution for joint venture for future development. Segments [Domain] Segments [Domain] Revenues Revenue from Purchased Water Revenue from Purchased Water Marketable securities with unrealized gains Gross unrealized holding gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Axis] Components of segment revenues Revenue from External Customers by Products and Services [Table Text Block] Entity Common Stock Shares Outstanding Entity Common Stock, Shares Outstanding Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] 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) Special taxes paid Taxes, Other Notional Amount Derivative, Notional Amount Accrued bonus Accrued Bonuses, Current Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Grapevine Grapevine [Member] Grapevine [Member] Other assets Other Assets, Noncurrent Investment in Unconsolidated and Consolidated Joint Ventures Equity Method Investments and Joint Ventures Disclosure [Text Block] Plan Name [Axis] Plan Name [Axis] SWP water contracts State Water Project Contracts [Member] State water project contracts. Reporting Segments and Related Information Segment Reporting Disclosure [Text Block] Dudley-Ridge water rights Dudley Ridge Water Rights [Member] Dudley Ridge Water Rights [Member] TOTAL ASSETS Assets Assets Related Party Transactions Related Party Transactions Disclosure [Text Block] Scenario [Axis] Scenario [Axis] 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 Title of 12(b) Security Title of 12(b) Security Schedule of accrued liabilities and other Schedule of Accrued Liabilities [Table Text Block] Net cost of purchased water contracts Finite-Lived Intangible Assets, Net Unrealized gain (loss) on available-for-sale securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Basis of Presentation Business Description and Basis of Presentation [Text Block] Estimated tax expense (benefit) of change in value of available-for-sale securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Depreciation and amortization Depreciation, Depletion and Amortization PEF Pastoria Energy Facility, LLC [Member] Pastoria Energy Facility, LLC [Member] TRCC-East TRCC-East [Member] TRCC-East [Member] Total liabilities Liabilities Building and Land Land and Building [Member] Total compensation cost not yet recognized, period for recognition Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Petro Travel Plaza Holdings, LLC Petro Travel Holdings Llc Plaza [Member] Petro travel holdings llc plaza. Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Retirement Plan Type [Axis] Retirement Plan Type [Axis] Fair market value of investment securities exceeds cost basis 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. 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 Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Total Debt Securities, Available for Sale Securities Maturities at Par Debt Securities, Available for sale securities maturities, at par. Real Estate [Abstract] Real Estate [Abstract] 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] Contract-based intangible assets Contract-Based Intangible Assets [Member] Additional Paid-In Capital Additional Paid-in Capital [Member] Total water held for future use and purchased water contracts Long Term Water Assets, Contracts with Company Long Term Water Assets, Contracts with Company Adjustments to reconcile net loss to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Litigation Case [Axis] Litigation Case [Axis] Corporate notes Corporate notes Corporate Note Securities [Member] Investment in unconsolidated joint ventures TRC equity Equity Method Investments Common stock, outstanding shares (in shares) Common Stock, Shares, Outstanding Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Ranch operations Ranch Operations [Member] Ranch Operations [Member] Excess tax shortfall from stock-based compensation Deferred Tax Expense from Stock Options Exercised Income taxes receivable Income Taxes Receivable Loss before income tax expense Operating results from commercial/industrial and unconsolidated joint ventures Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Letters of credit outstanding amount Letters of Credit Outstanding, Amount Common stock, authorized shares (in shares) Common Stock, Shares Authorized Common stock equivalents (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Schedule of real estate Schedule of Real Estate Properties [Table Text Block] Accrued vacation Accrued Vacation, Current Fair Value Estimate of Fair Value Measurement [Member] Statement of Operations Income Statement [Abstract] Accumulated Other Comprehensive (Loss) Income AOCI Attributable to Parent [Member] Gain realized on sale Gain (Loss) on Disposition of Assets Summary of maturities, at par, of marketable securities by year Investments Classified by Contractual Maturity Date [Table Text Block] Pension and supplemental executive retirement plan liability Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent Five West Parcel, LLC Five West Parcel Llc [Member] Five west parcel llc. Name of Property [Domain] Name of Property [Domain] 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] Schedule of Long Lived Assets Held-for-sale [Table] Schedule of Long Lived Assets Held-for-sale [Table] Current Assets: Assets, Current [Abstract] TRC-MRC 1, LLC TRC-MRC 1 LLC [Member] TRC-MRC 1 LLC [Member] Consolidated Entities [Axis] Consolidated Entities [Axis] Real estate - resort/residential Resort and Residential Real Estate [Member] Resort and Residential Real Estate [Member] Comprehensive income (loss) attributable to common stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent DMB DMB Pacific LLC [Member] DMB Pacific LLC [Member] Scenario [Domain] Scenario [Domain] Counterparty Name [Domain] Counterparty Name [Domain] Real estate and equipment expenditures Payments to Acquire Property, Plant, and Equipment Legal Entity [Axis] Legal Entity [Axis] City Area Code City Area Code Consolidation Items [Domain] Consolidation Items [Domain] Number of directors Number of Directors Number of Directors Document Period End Date Document Period End Date Mountain Village Tejon Mountain Village Llc [Member] Tejon mountain village llc. Equity in (losses) earnings of unconsolidated joint ventures, net Equity in losses (earnings) of unconsolidated joint ventures, net Equity in earnings (loss) Income (Loss) from Equity Method Investments Current investment mix Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Other Liabilities Other Liabilities Disclosure [Text Block] Net loss Net loss Net loss Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Loss from operations before equity in (losses) earnings of unconsolidated joint ventures Operating results Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest 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 Capitalized Share-based Payment Arrangement, Amount Capitalized Components of water assets Disclosure of Long Lived Assets Held-for-sale [Table Text Block] Summary of stock compensation costs for employee and NDSI plans Share-based Payment Arrangement, Cost by Plan [Table Text Block] Stock compensation expense Share-based Payment Arrangement, Noncash Expense 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. Entity [Domain] Entity [Domain] Taxes on vested stock grants Proceeds from (Payments for) Other Financing Activities 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] Restricted stock issuance (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Cover [Abstract] Cover [Abstract] TRC-MRC 4 LLC TRC-MRC 4 LLC [Member] TRC-MRC 4 LLC Summary of available-for-sale securities Debt Securities, Available-for-sale [Table Text Block] Distribution of earnings from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution Amortization of premium/discount of marketable securities Accretion (Amortization) of Discounts and Premiums, Investments Settled Litigation Settled Litigation [Member] Total available-for-sale securities Debt Securities, Available-for-sale Total expenses Segment losses Costs and Expenses Award Date [Domain] Award Date [Domain] Letter of credit period Letter of credit period Letter of credit period. Equity Components [Axis] Equity Components [Axis] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Land Land [Member] Majestic Realty Co. Majestic Realty Co. [Member] Majestic Realty Co. [Member] Consolidated Entities [Domain] Consolidated Entities [Domain] Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Award Date [Axis] Award Date [Axis] 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 Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Equities Defined Benefit Plan, Equity Securities [Member] 1998 Plan Stock Incentive Plan 1998 [Member] Stock incentive plan. Net loss attributable to non-controlling interest Net Income (Loss) Attributable to Noncontrolling Interest 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] Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures [Abstract] Net amortization and deferral Defined Benefit Plan, Amortization of Gain (Loss) 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] Entity Interactive Data Current Entity Interactive Data Current Total net periodic pension earnings Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Revenues: Revenues [Abstract] Value of property contributed Contribution of Property Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] 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 Equity Stockholders' Equity Note Disclosure [Text Block] Area of building owned and leased Lease of Building Lease of building. Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Interest Rate Swap Interest Rate Swap [Member] Additional paid-in capital Additional Paid in Capital, Common Stock 2022 Debt Securities, Available for Sale Securities Maturities, Year Two, at Par Debt Securities, Available for sale securities maturities, year two, at par. Entity Registrant Name Entity Registrant Name Number of tenants Joint Venture, Number of Tenants Joint Venture, Number of Tenants Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Less: deferred loan costs Annual cost related to the letter of credit Debt Issuance Costs, Net Non-cash write-off of leasing assets Non-cash Write-off of Tenant Receivables Non-cash Write-off of Tenant Receivables Number of reportable segments Number of Reportable Segments 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 Retirement Plan Type [Domain] Retirement Plan Type [Domain] Non-cash retirement plan expense Pension and Other Postretirement Benefits Cost (Reversal of Cost) Number of acres for development Development of Building Development of building. Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Consolidation Items [Axis] Consolidation Items [Axis] Investments in long-term water assets Payments to Acquire Other Investments Schedule of other liabilities Other Liabilities [Table Text Block] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Consolidated joint venture, ownership interest Noncontrolling Interest, Ownership Percentage by Parent Estimated future payments Lessee, Operating Lease, Liability, to be Paid (Gain) loss on sale of property plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Gross unrealized holding losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Entity Address, Postal Zip Code Entity Address, Postal Zip Code 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. Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Document Transition Report Document Transition Report Cost of sales Cost of Purchased Water Other Income: Nonoperating Income (Expense) [Abstract] 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 Additional bond debt authorized to be sold in future Debt instrument face amount Debt Instrument, Face Amount Level 2 Fair Value, Inputs, Level 2 [Member] Option period purchase price Investment in Joint Venture Option Period Purchase Price Investment in Joint Venture Option Period Purchase Price Document Quarterly Report Document Quarterly Report Earnings (cost) components: Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Farming Farming and Agriculture [Member] Farming and agriculture. Weighted Average Interest Pay Rate Derivative, Fixed Interest Rate Tangible water assets Tangible Water Assets [Table Text Block] Tangible Water Assets [Table Text Block] Deferred income Contract with Customer, Liability, Current Other Liabilities Other Liabilities [Member] Credit Facility [Domain] Credit Facility [Domain] Derivative Contract [Domain] Derivative Contract [Domain] Diluted shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Proceeds from sale of real estate/assets Proceeds from Sale of Real Estate Held-for-investment Litigation Case [Domain] Litigation Case [Domain] Net (loss) per share attributable to common stockholders, basic (in dollars per share) Earnings Per Share, Basic Entity File Number Entity File Number Expired/forfeited grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Debt Disclosure [Abstract] Debt Disclosure [Abstract] Property tax payable Accrual for Taxes Other than Income Taxes, Current SERP Supplemental Employee Retirement Plan [Member] Acres of land Related Party Transaction, Area of Land Related Party Transaction, Area of Land Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Repayments of long-term debt Repayments of Long-term Debt Total fair value of award Stock compensation costs, expensed Share-based Payment Arrangement, Expense Number of parties in agreement for settlement Loss Contingency, Number of Plaintiffs Balance Sheet Location [Axis] Balance Sheet Location [Axis] Tulare Lake Basin water rights Tulare Lake Basin Water Rights [Member] Tulare Lake Basin Water Rights [Member] Counterparty Name [Axis] Counterparty Name [Axis] Issued and outstanding shares - 26,336,115 at March 31, 2021 and 26,276,830 at December 31, 2020 Common Stock, Value, Issued Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Document Fiscal Year Focus Document Fiscal Year Focus Centennial Centennial Founders LLC [Member] Centennial Founders LLC Less: line-of-credit and current maturities of long-term debt Long-term Debt, Current Maturities Entity Current Reporting Status Entity Current Reporting Status Current maturities of long-term debt Debt, Current West CFD West Community Facilities Districts [Member] West community facilities districts. 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. Retirement Benefits [Abstract] Retirement Benefits [Abstract] Related Party Transaction [Axis] Related Party Transaction [Axis] Other Liabilities Disclosure [Abstract] Other Liabilities Disclosure [Abstract] Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Non-controlling interest Stockholders' Equity Attributable to Noncontrolling Interest Equity Method Investment, Nonconsolidated Investee [Domain] Equity Method Investment, Nonconsolidated Investee [Domain] Long-term Debt, Current and Noncurrent [Abstract] Long-term Debt, Current and Noncurrent [Abstract] Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Common stock, issued shares (in shares) Common Stock, Shares, Issued Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Less accumulated depreciation Inventory, Real Estate, Improvements, Accumulated Depreciation Inventory, Real Estate, Improvements, Accumulated Depreciation 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 Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Litigation Status [Axis] Litigation Status [Axis] Acre-Feet Sold Long Term Water Assets, Water Sold (Volume) Long Term Water Assets, Water Sold (Volume) Long-term debt, less current portion Long-term Debt, Excluding Current Maturities Segment Reporting [Abstract] Segment Reporting [Abstract] Treasury/Corporate Notes Defined Benefit Plan, Debt Security [Member] 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. KCWA Kern County Water Agency [Member] Kern County Water Agency [Member] Total Tejon Ranch Co. Stockholders’ Equity Stockholders' Equity Attributable to Parent Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Receivables, inventories, prepaids and other assets, net Increase (Decrease) in Operating Assets TOTAL LIABILITIES AND EQUITY Liabilities and Equity Other Other Employee-related Liabilities, Current Loss Contingencies [Line Items] Loss Contingencies [Line Items] Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Income Taxes Income Tax Disclosure [Text Block] Fair Value Derivative Assets (Liabilities), at Fair Value, Net Entity Address, City or Town Entity Address, City or Town Notes payable Notes Payable Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Current liabilities Increase (Decrease) in Operating Liabilities Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] 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] Schedule of interest rate derivatives Schedule of Interest Rate Derivatives [Table Text Block] Total Stockholders' Equity Parent [Member] Financial Instrument [Axis] Financial Instrument [Axis] Additional costs for future years Additional Reimbursement Funds, Costs Reserved For Future Years Additional Reimbursement Funds, Costs Reserved For Future Years Equity Component [Domain] Equity Component [Domain] 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 Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Axis] Earnings (Loss) Gross Profit Real Estate Real Estate Disclosure [Text Block] Property and equipment, net Property, Plant and Equipment, Net Entity Tax Identification Number Entity Tax Identification Number 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) 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] Net loss attributable to common stockholders Net Income (Loss) Attributable to Parent Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Investment, Name [Domain] Investment, Name [Domain] Other comprehensive gain (loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Annual option payment Long Term Water Assets, Purchased, Annual Option Payment, Percent Long Term Water Assets, Purchased, Annual Option Payment, Percent Long Lived Assets Held-for-sale by Asset Type [Axis] Long Lived Assets Held-for-sale by Asset Type [Axis] Total current assets Assets, Current Current Fiscal Year End Date Current Fiscal Year End Date Comprehensive loss attributable to non-controlling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest 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 Tejon Ranch Co. Stockholders’ Equity Stockholders' Equity Attributable to Parent [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Restricted stock issuance Stock Issued During Period, Value, Restricted Stock Award, Gross Long-term deferred gains Contract with Customer, Liability, Noncurrent Equity Method Investment, Nonconsolidated Investee or Group of Investees Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] Non-cash investing activities Supplemental Cash Flow Information [Abstract] Excess joint venture distributions and other Other Sundry Liabilities, Noncurrent Entity Filer Category Entity Filer Category Common Stock Shares Outstanding Common Stock [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] 2021 Debt Securities, Available for Sale Securities Maturities Year One at Par Debt Securities, Available for sale securities maturities, year one, at par. Distribution of equity from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution, Return of Capital (Expense) benefit for income taxes related to other comprehensive income items Other Comprehensive Income (Loss), Tax Costs Finite-Lived Intangible Assets, Gross Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] 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 Money market funds Money Market Funds [Member] Name of Property [Axis] Name of Property [Axis] Related Party Transactions [Abstract] Related Party Transactions [Abstract] Decrease in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Total other income Nonoperating Income (Expense) Summary of stock grant activity Schedule of Nonvested Share Activity [Table Text Block] Unrealized (loss) gain on available-for-sale securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment and Tax 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 Costs and Expenses: Costs and Expenses [Abstract] Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Investments in unconsolidated joint ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Ownership [Axis] Ownership [Axis] 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] Ownership [Domain] Ownership [Domain] Loss Contingencies [Table] Loss Contingencies [Table] Cost Reported Value Measurement [Member] 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 Plan Name [Domain] Plan Name [Domain] Unconsolidated joint ventures, ownership interest Equity Method Investment, Ownership Percentage Total equity Beginning balance, value Ending balance, value Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Acres of land transferred Acres of Land Transferred Acres of Land Transferred Revenues Commercial/industrial revenues Revenues Income tax expense Income Tax Expense (Benefit) 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 Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Funds invested in marketable securities Payments to Acquire Marketable Securities Net (loss) per share attributable to common stockholders, diluted (in dollars per share) Earnings Per Share, Diluted Local Phone Number Local Phone Number Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Components of long-term debt Schedule of Debt [Table Text Block] Total Stock Compensation Costs Share-based Payment Arrangement, Accelerated Cost 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] Investment income Investment Income, Net U.S. Treasury and agency notes U.S. Treasury and agency notes US Treasury and Government Short-term Debt Securities [Member] Entity Address, Address Line One Entity Address, Address Line One Related Party Transaction [Domain] Related Party Transaction [Domain] Entity Emerging Growth Company Entity Emerging Growth Company Accrued paid personal leave Accrued Paid Personal Leave, Current Accrued Paid Personal Leave, Current Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Antelope Valley Groundwater Cases Antelope Valley Groundwater Cases [Member] Antelope Valley Groundwater Cases [Member] Accrued interest receivable balance Accrued Investment Income Receivable Assumptions used in determining periodic pension cost: Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Award Type [Axis] Award Type [Axis] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Net loss Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Accumulated Depreciation Finite-Lived Intangible Assets, Accumulated Amortization Real estate and improvements - held for lease, net Real estate and improvements - held for lease, net Inventory, Real Estate, Improvements Maximum Maximum [Member] Noncontrolling Interest Noncontrolling Interest [Member] 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 Restricted cash Restricted Cash Retained Earnings Retained Earnings [Member] Rockefeller Joint Ventures Rockefeller Joint Ventures [Member] Rockefeller joint ventures. Measurement Basis [Axis] Measurement Basis [Axis] Unrealized gain (loss) on interest rate swap Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Components of net periodic pension cost Schedule of Net Benefit Costs [Table Text Block] Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities NDSI Plan Non-Employee Director Stock Incentive Plan [Member] Non-employee director stock incentive plan. Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Domain] Award Type [Domain] Trading Symbol Trading Symbol Water available for banking, sales, or internal use Long-term Water Assets, Transferrable Water (Volume) Long-term Water Assets, Transferrable Water (Volume) December 11 2020 December 11, 2020 [Member] December 11, 2020 Long-Term Water Assets Property, Plant and Equipment Disclosure [Text Block] Litigation Status [Domain] Litigation Status [Domain] Total purchased water contracts Long-term Water Assets, Intangible Water Contracts (Volume) Long-term Water Assets, Intangible Water Contracts (Volume) Pension plan Pension Plan [Member] Current Liabilities: Liabilities, Current [Abstract] Entity Shell Company Entity Shell Company Shares withheld for taxes and tax benefit of vested shares (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Balance Sheet Information Statement of Financial Position [Abstract] 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.