Balance Sheets (Unaudited) Balance Sheets (Unaudited) [Abstract] RealEstateAssigned [Domain] Assets Assets [Abstract] Cash and cash equivalents Accrued receivables Other assets Prepaid income taxes Notes receivable for land sales Water wells, vehicles, furniture, and equipment – at cost less accumulated depreciation Real estate acquired: Real estate acquired: [Abstract] Land Real estate and royalty interests assigned through the 1888 Declaration of Trust, no value assigned: Real estate and royalty interests assigned through the 1888 Declaration of Trust, no value assigned: [Abstract] An expense-free interest with a perpetual duration in oil or gas, as, if and when produced 1/16 of the proceeds are due to the Trust. Nonparticipating indicates the interest does not share in bonus or rental, nor in the right to execute leases or to explore and develop. 1/16 nonparticipating perpetual royalty interest in 373,777 acres in 2012 and 2011 an expense-free interest with a perpetual duration in oil or gas, as, if and when produced 1/128 of the proceeds are due to the Trust. Nonparticipating indicates the interest does not share in bonus or rental, nor in the right to execute leases or to explore and develop. 1/128 nonparticipating perpetual royalty interest in 85,414 acres in 2012 and 2011 Liabilities and Capital Liabilities and Capital [Abstract] Accounts payable and accrued expenses Income taxes payable Other taxes payable Unearned revenue Deferred taxes Pension plan liability Total liabilities Capital: Capital: [Abstract] Certificates of Proprietary Interest, par value $100 each; outstanding 0 certificates Sub-share Certificates in Certificates of Proprietary Interest, par value $.03 1/3 each; outstanding: 8,897,633 Sub-shares in 2012 and 9,175,414 Sub-shares in 2011 Other comprehensive loss Net proceeds from all sources Total capital Number of acres. Surface rights in acre as part of land owned. Number of lots. Represents the number of acres related to non-participating perpetual royalty interests. Acres Land (surface rights) Number of lots Nonparticipaing perpetual royalty interest in acres Certificates of Proprietary Interest, par value (in Dollars per share) Certificates of Proprietary Interest, outstanding (in Shares) Sub-share Certificates in Certificates of Proprietary Interest, par value (in Dollars per share) Sub-share Certificates in Certificates of Proprietary Interest, outstanding (in Shares) Statements of Income And Total Comprehensive Income (Unaudited) Statements of Income And Total Comprehensive Income (Unaudited) [Abstract] Income: Income: [Abstract] Rentals, royalties and sundry income Land sales Interest income from notes receivable Expenses: Expenses: [Abstract] Taxes, other than income taxes General and administrative expenses Operating income Interest income earned from investments Income before income taxes Income taxes Net income Other comprehensive income – periodic pension costs, net of income taxes of $6,117, $5,247, $18,350, and $15,742 respectively Total comprehensive income Average number of sub-share certificates and equivalent sub-share certificates outstanding (in Shares) Basic and dilutive earnings per sub-share certificate on net income (in Dollars per share) Cash dividends per sub-share certificate Net of income taxes Statements of Cash Flows (Unaudited) Statements of Cash Flows (Unaudited) [Abstract] Cash flows from operating activities: Cash flows from operating activities: [Abstract] Net income Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to reconcile net income to net cash provided by operating activities: [Abstract] Deferred taxes Depreciation and amortization Loss on disposal of fixed assets Changes in operating assets and liabilities: Changes in operating assets and liabilities: [Abstract] Accrued receivables and other assets Prepaid income taxes Notes receivable for land sales Accounts payable, accrued expenses and other liabilities Income taxes payable Net cash provided by operating activities Cash flows from investing activities: Cash flows from investing activities: [Abstract] Proceeds from sale of fixed assets Purchase of fixed assets Net cash used in investing activities Cash flows from financing activities: Cash flows from financing activities: [Abstract] Proprietary Interest Purchase of Sub-share Certificates in Certificates of Proprietary Interest Dividends paid Net cash used in financing activities Net increase (decrease) in cash and cash equivalents Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Note 1 Basis of Accounting [Text Block] Note 2 - Subsequent Events [Text Block] Note 3 - Property, Plant and Equipment Disclosure [Text Block] Note 4 - Conversion of Stock, Type of Stock Converted Note 5 - Income Tax Disclosure [Text Block] Note 6 - Quarterly Financial Information [Text Block] Note 7 - Cash and Cash Equivalents Disclosure [Text Block] Note 8 - Segment Reporting Disclosure [Text Block] Note 9 - Comprehensive Income (Loss) Note [Text Block] Significant Accounting Policies (Abstract) Significant Accounting Policies Subsequent Events, Policy [Policy Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Segment Reporting, Policy [Policy Text Block] Comprehensive Income, Policy [Policy Text Block] Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Supplemental cash flow information Supplemental cash flow information [Abstract] Income taxes paid The item represents the conversion ratio used in the conversion of equity shares. Number of shares used as part of calculation of ratio of Certificates of Proprietary Interest to Sub-share Certificates in Certificates of Proprietary Interest . Conversion Of Equity Number Of Shares Used In Ratio (in Shares) Effective Income Tax Rate, Continuing Operations Scenario [Axis] Scenario, Unspecified [Domain] Real Estate Assigned [Axis] Real Estate Assigned [Axis] Town Lots [Member] Town Lots [Member] Land Surface Rights [Member] Land Surface Rights [Member] Real Estate Acquired [Member] Real Estate Acquired [Member] Royalty Interests In Acres 1_ 128 [Member] Royalty Interests In Acres 1_128 [Member] Royalty Interests In Acres 1_128 [Member] Royalty Interests In Acres 1_ 16 [Member] Royalty Interests In Acres 1_16 [Member] Royalty Interests In Acres 1_16 [Member] Document and Entity Information [Abstract] NumberOfSharesUsedInRatio PropertyPlantAndEquipmentDisclosureTextBlockAbstract ConversionOfEquity ComprehensiveIncomeLossNoteTextBlockAbstract SubsequentEventsTextBlockAbstract ConversionOfStockTypeOfStockConvertedAbstract ProprietaryInterest IncomeTaxDisclosureTextBlockAbstract QuarterlyFinancialInformationTextBlockAbstract SegmentReportingDisclosureTextBlockAbstract CashAndCashEquivalentsDisclosureTextBlockAbstract BasisOfAccountingTextBlockAbstract Basis of Accounting [Text Block] Entity Filer Category Document Fiscal Year Focus Effective Income Tax Rate, Continuing Operations Segment Reporting, Policy [Policy Text Block] Entity Public Float Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Increase (Decrease) in Notes Receivables Entity Voluntary Filers Operating Income (Loss) Net Cash Provided by (Used in) Investing Activities Liabilities and Equity Document Period End Date Deferred Tax Liabilities, Net, Noncurrent Revenues Net Cash Provided by (Used in) Operating Activities Entity Current Reporting Status Comprehensive Income (Loss) Note [Text Block] Segment Reporting Disclosure [Text Block] Cash and Cash Equivalents, Period Increase (Decrease) Entity Registrant Name Subsequent Events, Policy [Policy Text Block] Gain (Loss) on Sale of Property Plant Equipment Amendment Flag Subsequent Events [Text Block] Payments to Acquire Property, Plant, and Equipment Cash and Cash Equivalents, Policy [Policy Text Block] Entity Well-known Seasoned Issuer Costs and Expenses Increase (Decrease) in Prepaid Taxes Entity Central Index Key Increase (Decrease) in Income Taxes Payable Increase (Decrease) in Deferred Income Taxes Stockholders' Equity Attributable to Parent Net Cash Provided by (Used in) Financing Activities Increase (Decrease) in Receivables Cash and Cash Equivalents Disclosure [Text Block] Amendment Description Document Type Income Tax Disclosure [Text Block] Entity Common Stock, Shares Outstanding Quarterly Financial Information [Text Block] Conversion of Stock, Type of Stock Converted Comprehensive Income, Policy [Policy Text Block] Comprehensive Income (Loss), Net of Tax, Attributable to Parent Liabilities Current Fiscal Year End Date Payments of Dividends Document Fiscal Period Focus Property, Plant and Equipment Disclosure [Text Block] Statement [Table] Statement [Line Items]