Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Investments, Debt and Equity Securities [Abstract] Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Share-based Payment Arrangement [Abstract] 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] Summary of stock grant activity Schedule of Nonvested Share Activity [Table Text Block] 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] Summary of stock compensation costs for Employee and NDSI Plans Share-based Payment Arrangement, Cost by Plan [Table Text Block] Statement of Comprehensive Income [Abstract] Net (loss) income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive (loss) income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Unrealized (loss) gain on available-for-sale securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Unrealized loss on interest rate swap Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Other comprehensive loss before taxes Other Comprehensive Income (Loss), before Tax Benefit for income taxes related to other comprehensive income items Other Comprehensive Income (Loss), Tax Other comprehensive loss Other Comprehensive Income (Loss), Net of Tax Comprehensive loss Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to non-controlling interests Net Income (Loss) Attributable to Noncontrolling Interest Comprehensive loss attributable to common stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent 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. Gross unrealized holding gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Gross unrealized holding losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Unrealized gain (loss) on available-for-sale securities 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 Accrued interest receivable balance Accrued Investment Income Receivable Segment Reporting [Abstract] Components of segment revenues Revenue from External Customers by Products and Services [Table Text Block] Payables and Accruals [Abstract] Accrued vacation Accrued Vacation, Current Accrued paid personal leave Accrued Paid Personal Leave, Current Accrued Paid Personal Leave, Current Accrued bonus Accrued Bonuses, Current Other Other Employee-related Liabilities, Current Total Other Accrued Liabilities, Current Accrued Liabilities and Other Accounts Payable and Accrued Liabilities Disclosure [Text Block] Real Estate [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Mountain Village Tejon Mountain Village Llc [Member] Tejon mountain village llc. Centennial Centennial Founders LLC [Member] Centennial Founders LLC Grapevine Grapevine [Member] Grapevine [Member] Tejon Ranch Commerce Center Tejon Ranch Commerce Center [Member] Tejon Ranch Commerce Center [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Real estate development Inventory, Real Estate, Land and Land Development Costs Tejon Ranch Commerce Center Inventory, Real Estate, Improvements, Gross Inventory, Real Estate, Improvements, Gross Less accumulated depreciation Inventory, Real Estate, Improvements, Accumulated Depreciation Inventory, Real Estate, Improvements, Accumulated Depreciation Real estate and improvements - held for lease, net Inventory, Real Estate, Improvements Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Certificates of deposit Certificates of Deposit [Member] U.S. Treasury and agency notes US Treasury and Government Short-term Debt Securities [Member] Corporate notes Corporate Note Securities [Member] Municipal notes Municipal Bonds [Member] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] 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. 2020 Debt Securities, Available for Sale Securities Maturities Year One at Par Debt Securities, Available for sale securities maturities, year one, at par. 2021 Debt Securities, Available for Sale Securities Maturities, Year Two, at Par Debt Securities, Available for sale securities maturities, year two, at par. Total Debt Securities, Available for Sale Securities Maturities at Par Debt Securities, Available for sale securities maturities, at par. 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 [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] Performance share grants Performance Shares [Member] Award Date [Axis] Award Date [Axis] Award Date [Domain] Award Date [Domain] December 12, 2019 December 12, 2019 [Member] December 12, 2019 [Member] March 11, 2020 March 11, 2020 [Member] March 11, 2020 [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] 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 Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate 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 Shares granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Total fair value of award Share-based Payment Arrangement, Expense Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Statement [Line Items] Statement [Line Items] Common stock, par value per share (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, authorized shares (in shares) Common Stock, Shares Authorized Common stock, issued shares (in shares) Common Stock, Shares, Issued Common stock, outstanding shares (in shares) Common Stock, Shares, Outstanding Accounting Policies [Abstract] Number of reportable segments Number of Reportable Segments Percentage of rent billings retained Rent Billings, Percentage Retained Rent Billings, Percentage Retained Percentage of rent billings deferred Rent Billings, Percentage Deferred Rent Billings, Percentage Deferred Deferred rent billings Deferred Rent Receivables, Net Retirement Benefits [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension plan Pension Plan [Member] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Equities Defined Benefit Plan, Equity Securities [Member] Treasury/Corporate Notes Defined Benefit Plan, Debt Security [Member] Money market funds Money Market Funds [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Service period Defined Benefit Plan, Average Service Period Defined Benefit Plan, Average Service Period Contributions to defined benefit plan Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year Current investment policy targets: Defined Benefit Plan, Plan Assets, Allocations [Abstract] Current investment mix Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Assumptions used in determining periodic pension cost: Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate 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 Stockholders' Equity Note [Abstract] Weighted average number of shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Common stock (in shares) Weighted Average Number of Shares Outstanding, Basic Common stock equivalents (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Restricted stock excluded from the calculation of dilutive net income per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] 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. Income Statement [Abstract] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Corporate expenses Corporate, Non-Segment [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Real estate - commercial/industrial Commercial and Industrial [Member] Commercial and industrial. Real estate - resort/residential Resort and Residential Real Estate [Member] Resort and Residential Real Estate [Member] Mineral resources Mineral Resources [Member] Mineral Resources [Member] Farming Farming and Agriculture [Member] Farming and agriculture. Ranch operations Ranch Operations [Member] Ranch Operations [Member] Revenues: Revenues [Abstract] Total revenues Revenue from Contract with Customer, Excluding Assessed Tax Costs and Expenses: Costs and Expenses [Abstract] Total expenses Costs and Expenses Operating loss Operating Income (Loss) Other Income: Nonoperating Income (Expense) [Abstract] Investment income Investment Income, Net Gain on sale of real estate Gains (Losses) on Sales of Investment Real Estate Other income, net Other Nonoperating Income (Expense) Total other income Nonoperating Income (Expense) Loss from operations before equity in earnings of unconsolidated joint ventures Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Equity in earnings of unconsolidated joint ventures, net Income (Loss) from Equity Method Investments (Loss) income before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) Net (loss) income Net income attributable to non-controlling interest Net (loss) income attributable to common stockholders Net Income (Loss) Attributable to Parent Net (loss) income per share attributable to common stockholders, basic (in dollars per share) Earnings Per Share, Basic Net (loss) income per share attributable to common stockholders, diluted (in dollars per share) Earnings Per Share, Diluted Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 2 Fair Value, Inputs, Level 2 [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swap Interest Rate Swap [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other Liabilities Other Liabilities [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Weighted Average Interest Pay Rate Derivative, Fixed Interest Rate Fair Value Derivative Assets (Liabilities), at Fair Value, Net Notional Amount Derivative, Notional Amount Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Petro Travel Plaza Holdings, LLC Petro Travel Holdings Llc Plaza [Member] Petro travel holdings llc plaza. Majestic Realty Co. Majestic Realty Co. [Member] Majestic Realty Co. [Member] TRC-MRC 3, LLC TRC-MRC 3 LLC [Member] TRC-MRC 3 LLC [Member] TRC-MRC 2, LLC TRC-MRC 2 LLC [Member] TRC-MRC 2 LLC [Member] TRCC-East TRCC-East [Member] TRCC-East [Member] TRC-MRC 1, LLC TRC-MRC 1 LLC [Member] TRC-MRC 1 LLC [Member] Rockefeller Joint Ventures Rockefeller Joint Ventures [Member] Rockefeller joint ventures. Five West Parcel, LLC Five West Parcel Llc [Member] Five west parcel llc. 18-19 West, LLC Eighteen Nineteen West Llc [Member] Eighteen nineteen west llc. TRCC/Rock Outlet Center, LLC TRCC/Rock Outlet Center [Member] TRCC/Rock Outlet Center [Member] Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] Building and Land Land and Building [Member] Land Land [Member] Building Development Building Improvements [Member] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Investments in unconsolidated joint ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Equity in earnings (loss) Unconsolidated joint ventures, ownership interest Equity Method Investment, Ownership Percentage 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) Investment in unconsolidated joint ventures Equity Method Investments Value of property contributed Contribution of Property Gain realized on sale Gain (Loss) on Disposition of Assets Number of joint venture contracts Number of Joint Venture Contracts Number of joint venture contracts. Number of acres for development Development of Building Development of building. Lease agreement, rentable space Joint Venture, Percentage of Rentable Space Occupied Joint Venture, Percentage of Rentable Space Occupied Debt Borrowings Borrowings Area of building owned and leased Lease of Building Lease of building. Debt instrument face amount Debt Instrument, Face Amount Deficit balance Distributions in Excess of Investment in Unconsolidated Joint Venture Distributions in Excess of Investment in Unconsolidated Joint Venture 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 Development of land in TRCC including pursuing foreign trade zone (up to) Area of Land Purchase price Proceeds from Sale of Building to Third Party Proceeds from Sale of Building to Third Party Number of acres for development Contribution for Joint Venture for Future Development Contribution for joint venture for future development. Option period purchase price Investment in Joint Venture, Option Period, Purchase Price Investment in Joint Venture, Option Period, Purchase Price Purchase price, increase amount Investment in Joint Venture, Purchase Price, Increase Amount Investment in Joint Venture, Purchase Price, Increase Amount Construction loan percent of costs Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Construction Loan Costs, Percent Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Construction Loan Costs, Percent Equity contributions Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Equity Contributions, Percent Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Equity Contributions, Percent Number of members Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Number of Members Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Number of Members Consolidated joint venture, ownership interest Noncontrolling Interest, Ownership Percentage by Parent SERP Supplemental Employee Retirement Plan [Member] Earnings (cost) components: Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Net amortization and deferral Defined Benefit Plan, Amortization of Gain (Loss) Total net periodic pension earnings Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Statement of Cash Flows [Abstract] Transaction costs Contribution of Property, Transaction Costs Contribution of Property, Transaction Costs Profit margin Gross Profit Deferred profit margin Equity Method Investment, Deferred Gain on Sale Reporting Segments and Related Information Segment Reporting Disclosure [Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Notes payable Secured Debt [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Long-term debt consists of: Long-term Debt, by Current and Noncurrent [Abstract] Total short-term and long-term debt Long-term Debt, Gross Less: current maturities of long-term debt Long-term Debt, Current Maturities Less: deferred loan costs Debt Issuance Costs, Net Long-term debt, less current portion Long-term Debt, Excluding Current Maturities Interest Rate Swap Derivative Instruments and Hedging Activities Disclosure [Text Block] 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] Stock grants outstanding beginning of the year at target achievement (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number New stock grants/additional shares due to maximum achievement (in shares) Vested grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Expired/forfeited grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Stock grants outstanding end of the year at target achievement (in shares) Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Total revenues Revenues Segment losses Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Total Stockholders' Equity Parent [Member] Common Stock Common Stock [Member] Additional Paid-In Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive (Loss) Income AOCI Attributable to Parent [Member] Retained Earnings Retained Earnings [Member] Noncontrolling Interest Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance, value Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning Balance (in shares) Shares, Outstanding Net income (loss) Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Other comprehensive income (loss) Restricted stock issuance Stock Issued During Period, Value, Restricted Stock Award, Gross Restricted stock issuance (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Stock compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Shares withheld for taxes and tax benefit of vested shares Share-based Payment Arrangement, Decrease for Tax Withholding Obligation Shares withheld for taxes and tax benefit of vested shares (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Ending Balance, value Ending Balance (in shares) Below threshold performance (in shares) Performance Awards Granted with Performance Conditions, Number of Shares to be Issued, Below Threshold Performance Performance Awards Granted with Performance Conditions, Number of Shares to be Issued, Below Threshold Performance 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 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 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 ASSETS Assets [Abstract] Current Assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Marketable securities - available-for-sale Debt Securities, Available-for-sale, Current Accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Inventories Inventory, Net Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Real estate and improvements - held for lease, net Real estate development (includes $106,494 at June 30, 2020 and $104,491 at December 31, 2019, attributable to Centennial Founders, LLC, Note 15) Property and equipment, net Property, Plant and Equipment, Net Net investment in water assets Long Term Assets Held for Future Use or Sale Long term assets held for future use or sale. Deferred tax assets Deferred Income Tax Assets, Net Other assets Other Assets, Noncurrent TOTAL ASSETS Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Current Liabilities: Liabilities, Current [Abstract] Trade accounts payable Accounts Payable, Current Accrued liabilities and other Deferred income Contract with Customer, Liability, Current Current maturities of long-term debt Debt, Current Total current liabilities Liabilities, Current Long-term deferred gains Contract with Customer, Liability, Noncurrent Other liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Tejon Ranch Co. Stockholders’ Equity Stockholders' Equity Attributable to Parent [Abstract] Issued and outstanding shares - 26,221,862 at June 30, 2020 and 26,096,797 at December 31, 2019 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) Total Tejon Ranch Co. Stockholders’ Equity Stockholders' Equity Attributable to Parent Non-controlling interest Stockholders' Equity Attributable to Noncontrolling Interest Total equity TOTAL LIABILITIES AND EQUITY Liabilities and Equity Schedule of Interest Rate Derivatives Schedule of Interest Rate Derivatives [Table Text Block] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 1998 Plan Stock Incentive Plan 1998 [Member] Stock incentive plan. NDSI Plan Non-Employee Director Stock Incentive Plan [Member] Non-employee director stock incentive plan. Stock compensation costs, expensed Stock compensation costs, capitalized Share-based Payment Arrangement, Amount Capitalized Total Stock Compensation Costs Share-based Payment Arrangement, Accelerated Cost Cover [Abstract] Document Type Document Type Document Quarterly Report Document Quarterly Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock Shares Outstanding Entity Common Stock, Shares Outstanding Goodwill and Intangible Assets Disclosure [Abstract] 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] Tangible water assets Tangible Water Assets [Table Text Block] Tangible Water Assets [Table Text Block] Schedule of finite-lived intangible assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Components of water assets Disclosure of Long Lived Assets Held-for-sale [Table Text Block] Components of long-term debt Schedule of Debt [Table Text Block] Retirement Plans Retirement Benefits [Text Block] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Cost Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Certificates of deposit U.S. Treasury and agency notes Corporate notes Municipal notes Level 1 Fair Value, Inputs, Level 1 [Member] Marketable Securities with unrecognized losses for less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Marketable Securities with unrecognized losses for more than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Marketable Securities with unrecognized gains Total Available-for-sale Securities Debt Securities, Available-for-sale Schedule of Real Estate Schedule of Real Estate Properties [Table Text Block] Commercial/industrial revenues 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 Operating results from commercial/industrial and unconsolidated joint ventures Schedule of Long Lived Assets Held-for-sale [Table] Schedule of Long Lived Assets Held-for-sale [Table] Long Lived Assets Held-for-sale by Asset Type [Axis] Long Lived Assets Held-for-sale by Asset Type [Axis] Long Lived Assets Held-for-sale, Name [Domain] Long Lived Assets Held-for-sale, Name [Domain] Banked water and water for future delivery Banked Water and Water for Future Delivery [Member] Banked water and water for future delivery. Transferable water Transferable Water [Member] Transferable water. Long Lived Assets Held-for-sale [Line Items] Long Lived Assets Held-for-sale [Line Items] Total water held for future use at cost Tangible Water Assets, Banked Water and Water Contract Rights Tangible Water Assets, Banked Water and Water Contract Rights Loss Contingencies [Table] Loss Contingencies [Table] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] DMB DMB Pacific LLC [Member] DMB Pacific LLC [Member] KCWA Kern County Water Agency [Member] Kern County Water Agency [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] West CFD West Community Facilities Districts [Member] West community facilities districts. East CFD East Community Facilities Districts [Member] -- None. No documentation exists for this element. -- Standby letter of credit Standby Letters of Credit [Member] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Antelope Valley Groundwater Cases Antelope Valley Groundwater Cases [Member] Antelope Valley Groundwater Cases [Member] Litigation Status [Axis] Litigation Status [Axis] Litigation Status [Domain] Litigation Status [Domain] Settled Litigation Settled Litigation [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Amount expected to be paid Purchase Commitment, Remaining Minimum Amount Committed Payments for water contracts Operating Lease, Payments Contract renewal optional term Long Term Water Assets, Contract Renewal Optional Term Long Term Water Assets, Contract Renewal Optional Term Long-term water assets (volume) Long-term Water Assets (Volume) Long-term Water Assets (Volume) Contractual obligation for future water payments Contractual Obligation Estimated future payments Lessee, Operating Lease, Liability, to be Paid 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 Number of community facility districts Number of Community Facility Districts Number of Community Facility Districts Acres of land related to land liens Acres of Land Related to Land Liens Acres of land related to land liens. Bond debt sold by TRPFFA Long-term Line of Credit Additional bond debt authorized to be sold in future Letters of credit outstanding amount Letters of Credit Outstanding, Amount Letter of credit period Letter of credit period Letter of credit period. Letter of credit renewal period Letter of Credit Renewal Period Letter of credit renewal period. Annual cost related to the letter of credit Additional reimbursement funds Additional Reimbursement Funds Additional reimbursement funds. Special taxes paid Taxes, Other Number of parties in agreement for settlement Loss Contingency, Number of Plaintiffs 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 Acres of land transferred Acres of Land Transferred Acres of Land Transferred SWP water contracts State Water Project Contracts [Member] State water project contracts. PEF Pastoria Energy Facility, LLC [Member] Pastoria Energy Facility, LLC [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Maximum Maximum [Member] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Ranchcorp Subsidiaries [Member] 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) Long-term water assets (in acre-feet) Cost of purchased water (per acre-foot) Cost of Purchased Water, Area Cost of Purchased Water, Area Annual fee increase, percent Long Term Water Assets, Purchased, Annual Fee Increase, Percent Long Term Water Assets, Purchased, Annual Fee Increase, Percent 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 Annual option payment, percent Long Term Water Assets, Purchased, Annual Option Payment, Percent Long Term Water Assets, Purchased, Annual Option Payment, Percent Operating results Schedule of weighted average number of shares outstanding Schedule of Weighted Average Number of Shares [Table Text Block] Schedule of Accrued Liabilities and Other Schedule of Accrued Liabilities [Table Text Block] Real Estate Real Estate Disclosure [Text Block] Investment in Unconsolidated and Consolidated Joint Ventures Equity Method Investments and Joint Ventures Disclosure [Text Block] Long-Term Water Assets Property, Plant and Equipment Disclosure [Text Block] Recent and Newly Adopted Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Income taxes receivable Income Taxes Receivable Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Contract-based intangible assets Contract-Based Intangible Assets [Member] Dudley-Ridge water rights Dudley Ridge Water Rights [Member] Dudley Ridge Water Rights [Member] Nickel water rights Nickel Water Rights [Member] Nickel Water Rights [Member] Tulare Lake Basin water rights Tulare Lake Basin Water Rights [Member] Tulare Lake Basin Water Rights [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Costs Finite-Lived Intangible Assets, Gross Accumulated Depreciation Finite-Lived Intangible Assets, Accumulated Amortization Net cost of purchased water contracts Finite-Lived Intangible Assets, Net Total tangible water assets Net investment in water assets Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Domain] Equity Method Investment, Nonconsolidated Investee [Domain] Equity Method Investment, Nonconsolidated Investee or Group of Investees Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] Statement of Operations Joint Venture Earnings(Loss) TRC Equity in Earnings (Loss) Equity In Earnings (Loss) Equity In Earnings (Loss) 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 Balance Sheet Information Joint Venture Assets Joint Venture Debt Joint Venture Equity TRC Equity 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 Total compensation cost not yet recognized Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Total compensation cost not yet recognized, period for recognition Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Basis of Presentation Business Description and Basis of Presentation [Text Block] Water held for future use Antelope Valley East Kern Water Agency [Member] Antelope valley east kern water agency. WRMWSD - Contracts with the Company Wheeler Ridge Maricopa Water Storage District [Member] Wheeler Ridge Maricopa Water Storage District [Member] Tejon-Castac Water District Tejon-Castac Water District [Member] Tejon-Castac Water District [Member] Long-term Water Assets [Line Items] Long-term Water Assets [Line Items] Long-term Water Assets [Line Items] Banked water and water for future delivery Long-term Water Assets, Banked Water and Water Contract Rights [Abstract] Long-term Water Assets, Banked Water and Water Contract Rights [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) Transferable water Long-term Water Assets, Transferrable Water (Volume) Long-term Water Assets, Transferrable Water (Volume) Banked water and water for future delivery Long-term Water Assets, Banked Water and Water Contract Rights (Volume) Long-term Water Assets, Banked Water and Water Contract Rights (Volume) Water contracts and purchased water Long-term Water Assets, Water Contracts (Volume) Long-term Water Assets, Water Contracts (Volume) Total purchased water contracts Long-term Water Assets, Intangible Water Contracts (Volume) Long-term Water Assets, Intangible Water Contracts (Volume) Total purchased and contracted water sources in acre feet Long Term Water Assets, Contracts with Company Long Term Water Assets, Contracts with Company Summary of available-for-sale securities Debt Securities, Available-for-sale [Table Text Block] Summary of maturities, at par, of marketable securities by year Investments Classified by Contractual Maturity Date [Table Text Block] Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net (loss) income Adjustments to reconcile net (loss) income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Amortization of premium/discount of marketable securities Accretion (Amortization) of Discounts and Premiums, Investments Equity in earnings of unconsolidated joint ventures, net Non-cash retirement plan expense Pension and Other Postretirement Benefits Cost (Reversal of Cost) Non-cash profits recognized from land contribution Gain (Loss) on Disposition of Other Assets Non-cash write-off of leasing assets Non-cash Write-off of Tenant Receivables Non-cash Write-off of Tenant Receivables Gain on sale of property plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Deferred income taxes Deferred Income Tax Expense (Benefit) Stock compensation expense Share-based Payment Arrangement, Noncash Expense Excess tax benefit from stock-based compensation Deferred Tax Expense from Stock Options Exercised Distribution of earnings from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Receivables, inventories, prepaids and other assets, net Increase (Decrease) in Operating Assets Current liabilities, net Increase (Decrease) in Operating Liabilities Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Maturities and sales of marketable securities Proceeds from Sale and Maturity of Marketable Securities Funds invested in marketable securities Payments to Acquire Marketable Securities Real estate and equipment expenditures Payments to Acquire Property, Plant, and Equipment Proceeds from sale of real estate/assets Proceeds from Sale of Real Estate Held-for-investment Investment in unconsolidated joint ventures Payments to Acquire Interest in Joint Venture Distribution of equity from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution, Return of Capital Investments in long-term water assets Payments to Acquire Other Investments Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Repayments of long-term debt Repayments of Long-term Debt Taxes on vested stock grants Proceeds from (Payments for) Other Financing Activities Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Decrease in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents at end of period Non-cash investing activities Supplemental Cash Flow Information [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 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 Contribution to unconsolidated joint venture Long term deferred profit on land contribution Deferred Gain On Contribution Of Land Deferred Gain On Contribution Of Land Equity Stockholders' Equity Note Disclosure [Text Block] Acre-Feet Sold (in acre-feet) Long Term Water Assets, Water Sold (Volume) Long Term Water Assets, Water Sold (Volume) Revenues Revenue from Purchased Water Revenue from Purchased Water Cost of sales Cost of Purchased Water Profit Gross Profit from Purchased Water Gross Profit from Purchased Water Other Liabilities Disclosure [Abstract] Other Liabilities Other Liabilities Disclosure [Text Block] Components of net periodic pension cost Schedule of Net Benefit Costs [Table Text Block] Other Liabilities Other Liabilities [Abstract] Pension and supplemental executive retirement plan liability Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent Interest rate swap liability Derivative Liability, Noncurrent Excess joint venture distributions and other Other Sundry Liabilities, Noncurrent Total Line of Credit and Long-Term Debt Debt Disclosure [Text Block] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Wheeler Ridge Maricopa Water Storage District Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Executive Vice President and Chief Operating Officer Management [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Acres of land Related Party Transaction, Area of Land Related Party Transaction, Area of Land Purchased water contracts Related Party Transaction, Long-term Water Assets, Water Contracts (Volume) Related Party Transaction, Long-term Water Assets, Water Contracts (Volume) Water contracts and related costs Related Party Transaction, Amounts of Transaction Line of Credit Facility [Table] Line of Credit Facility [Table] Term Notes Medium-term Notes [Member] Revolving line of credit Revolving Credit Facility [Member] Promissory note agreement Notes Payable, Other Payables [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Selected LIBOR rate Selected LIBOR Rate [Member] Selected LIBOR Rate [Member] LIBOR for a fixed rate term Fixed Term LIBOR [Member] Fixed Term LIBOR [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Long-term debt Long-term Debt Interest pay rate Line of credit amount Line of Credit Facility, Current Borrowing Capacity RLC outstanding balance Interest rate on line of credit, variable rate Debt Instrument, Basis Spread on Variable Rate Commitment fee percentage Line of Credit Facility, Commitment Fee Percentage Number of debt covenants Debt Instrument, Covenant Compliance, Number of Covenants Debt Instrument, Covenant Compliance, Number of Covenants Debt equity ratio Debt Covenant Compliance, Debt Equity Ratio Debt Covenant Compliance, Debt Equity Ratio Debt service coverage ratio Debt Covenant Compliance, Debt Service Coverage Ratio Debt Covenant Compliance, Debt Service Coverage Ratio Minimum liquid assets Debt Covenant Compliance, Liquid Assets, Minimum Debt Covenant Compliance, Liquid Assets, Minimum Stated interest rate Debt Instrument, Interest Rate, Stated Percentage Periodic principal and interest payments Debt Instrument, Periodic Payment Additional payment Repayments of Notes Payable Principal monthly payments Debt Instrument, Periodic Payment, Principal Other Liabilities Other Liabilities [Table Text Block] 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.