Accrued postretirement benefit cost Liability, Other Postretirement Defined Benefit Plan, Noncurrent Due after five years through ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Accumulated Other Comprehensive Earnings (Losses) Note [Text Block] Comprehensive Income (Loss) Note [Text Block] Interest and dividend income Investment Income, Net Operating lease liabilities Operating Lease, Liability, Noncurrent Investments AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Net earnings Net earnings Net earnings Net Income (Loss) Attributable to Parent Consolidated Entities [Axis] Consolidated Entities [Axis] Entity Emerging Growth Company Entity Emerging Growth Company Change for ESOP related shares Temporary Equity, Carrying Amount, Period Increase (Decrease) Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Salaries and wages Employee-related Liabilities, Current City Area Code City Area Code Statistical Measurement [Domain] Statistical Measurement [Domain] Retained earnings Retained Earnings (Accumulated Deficit) Entity Address, Address Line One Entity Address, Address Line One Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Self-insurance reserves Self Insurance Reserve, Current Dividends, Common Stock, Cash Dividends, Common Stock, Cash Equity Securities Equity Securities, FV-NI, Current Proceeds from sale of property, plant and equipment Proceeds from Sale of Property, Plant, and Equipment Income Statement [Abstract] Income Statement [Abstract] Amendment Flag Amendment Flag Additional paid-in capital Additional Paid in Capital, Common Stock Entity Filer Category Entity Filer Category Other noncurrent assets Other Assets, Noncurrent Other operating income Other Operating Income Short-term investments Short-term Investments Retirement Benefits [Abstract] Retirement Benefits [Abstract] Net increase in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Income tax expense Income Tax Expense (Benefit) Contribution of shares to retirement plans Stock Issued During Period, Shares, Employee Stock Ownership Plan Income taxes Increase (Decrease) in Income Taxes Payable Trade receivables Accounts Receivable, after Allowance for Credit Loss, Current Equity Components [Axis] Equity Components [Axis] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Total current assets Assets, Current Document Fiscal Year Focus Document Fiscal Year Focus Subsequent Event Type [Domain] Subsequent Event Type [Domain] Entity File Number Entity File Number Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Equity Method Investments and Joint Ventures [Abstract] Fair Value [Abstract] Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Total adjustments Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Current portion of long-term debt Long-term Debt, Current Maturities Contribution of shares to retirement plans Stock Issued During Period, Value, Employee Stock Ownership Plan Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Small Business Entity Small Business Subsequent Events [Abstract] Subsequent Events [Abstract] Other operating cash receipts Proceeds from Other Operating Activities Equity Component [Domain] Equity Component [Domain] Unrealized Gains Debt Securities, Available-for-sale, Unrealized Gain Unrealized gain (loss) on debt securities net of income taxes in 2021 and 2020, respectively. Unrealized gain (loss) on debt securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Statements of Stockholders' Equity (Parenthetical) [Abstract] Statements of Stockholders' Equity (Parenthetical) [Abstract] Statements of Stockholders' Equity (Parenthetical) [Abstract] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] ASSETS Assets [Abstract] Total fair value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value Available For Sale Debt Securities [Table Text Block] Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Statement [Line Items] Statement [Line Items] Amortized Cost and Fair Value of Available For Sale Debt Securities by Expected Maturity [Table Text Block] Investments Classified by Contractual Maturity Date [Table Text Block] Earnings per share Earnings Per Share, Basic and Diluted Payment for investments Payments to Acquire Investments Available-for-sale Securities, Debt Maturities [Abstract] Available-for-sale Securities, Debt Maturities [Abstract] Entity Address, City or Town Entity Address, City or Town Fair Value Debt Securities, Available-for-sale Retained Earnings Retained Earnings [Member] Proceeds from sale and maturity of investments Proceeds from Sale, Maturity and Collection of Investments Other assets Increase (Decrease) in Prepaid Expense and Other Assets Debt Securities, Available-for-sale [Abstract] Debt Securities, Available-for-sale [Abstract] Fair Value of Financial Instruments [Text Block] Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block] Accrued expenses: Accrued Liabilities, Current [Abstract] Entity Address, State or Province Entity Address, State or Province Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Self-insurance reserves Self Insurance Reserve, Noncurrent Unrealized Loss Position, Fair Value Debt Securities, Available-for-sale, Unrealized Loss Position Entity [Domain] Entity [Domain] Available For Sale Debt Securities in an Unrealized Loss Position by Time Period Impaired [Table Text Block] Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block] Amortized Cost Total amortized cost Debt Securities, Available-for-sale, Amortized Cost Shopping Center Loans [Member] Secured Debt [Member] Dividends Payable, Date of Record Dividends Payable, Date of Record Total equity Total Equity Total of all equity items, net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Entity Shell Company Entity Shell Company Local Phone Number Local Phone Number Investment income Investment Income, Nonoperating ESOP, shares cost Employee Stock Ownership Plan Share Cost The cost of ESOP shares subject to put option as of the balance sheet date. Entity Interactive Data Current Entity Interactive Data Current Proceeds from sale of common stock Proceeds from Issuance of Common Stock Total assets Assets Assets Common stock, shares authorized Common Stock, Shares Authorized Dividends Payable, Date to be Paid Dividends Payable, Date to be Paid Net gain on sale of equity securities previously recognized through fair value adjustment Equity Securities, FV-NI, Realized Gain (Loss) Gain on investments Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments Inventories Increase (Decrease) in Retail Related Inventories Document Type Document Type Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Due after one year through five years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Other operating cash payments Payments for Other Operating Activities Investment income before fair value adjustment Investment Income Before Fair Value Adjustment This item represents investment income derived from investments in debt and equity securities consisting of interest income earned from investments in debt securities and on cash and cash equivalents, dividend income from investments in equity securities, and income or expense derived from the amortization of investment related discounts or premiums, respectively, net of related investment expenses. This item also includes realized gains or losses on the sale of debt and equity securities. Excludes unrealized gains on equity securities holdings. Prepaid expenses Prepaid Expense, Current Entity Current Reporting Status Entity Current Reporting Status Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Reclassification adjustment for net realized gain on debt securities net of income taxes in 2021 and 2020, respectively. Net realized gain on debt securities reclassified to investment income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Entity Tax Identification Number Entity Tax Identification Number JV Loans [Member] Construction Loans [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Amortized Cost [Abstract] Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract] Operating Cash Flows, Direct Method [Abstract] Operating Cash Flows, Direct Method [Abstract] Distributed shares subject to put option, fair value Employee Stock Ownership Plan Put Option Distributed Shares Fair Value Fair value of distributed ESOP shares subject to put option as of balance sheet date. Income taxes paid Income Taxes Paid, Net Subsequent Events [Text Block] Subsequent Events [Text Block] Comprehensive earnings Comprehensive earnings Comprehensive Income (Loss), Net of Tax, Attributable to Parent Common stock related to ESOP Common Stock Related To Employee Stock Ownership Plan Common Stock Related to Employee Stock Ownership Plan Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Document Transition Report Document Transition Report Other Comprehensive Earnings [Abstract] Other Comprehensive Income (Loss), Net of Tax [Abstract] Treasury stock at cost, 5,511 shares in 2021 Treasury Stock, Value Deferred income taxes Deferred Income Tax Liabilities, Net Tax exempt bonds [Member] Nontaxable Municipal Bonds [Member] Loans Assumed Loans Assumed Total liabilities and stockholders' equity Liabilities and Equity Other Other Accrued Liabilities, Current Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Taxable bonds [Member] Corporate Debt Securities [Member] Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity, Primary Beneficiary [Member] Accounts payable Accounts Payable, Current Trade receivables Increase (Decrease) in Accounts and Other Receivables Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract] Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract] Dividends per share Dividends, Common Stock Entities [Table] Entities [Table] Adjustment to postretirement benefit obligation net of income taxes in 2021 and 2020, respectively Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Accumulated Other Comprehensive Earnings (Losses) AOCI Attributable to Parent [Member] Equity Securities [Table] Marketable Securities [Table] Reconciliation of net earnings to net cash provided by operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Long-term investments Long-term Investments Financial Instruments [Domain] Financial Instruments [Domain] Acquisition of shares from stockholders Treasury Stock, Value, Acquired, Cost Method Due after five years through ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 ESOP shares, fair value Employee Stock Ownership Plan (ESOP), Fair Value of Shares Subject to Repurchase Obligation Cost of merchandise sold Cost of Goods and Services Sold Revenues: Revenues [Abstract] Retirement Plan [Text Block] Retirement Plans [Text Block] Retirement Plans. Minimum [Member] Minimum [Member] Basis of Presentation [Text Block] Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Restricted investments [Member] Debt Securities, Restricted [Member] Debt Securities, Restricted [Member] Fair Value of Financial Instruments [Table Text Block] Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Consolidated Entities [Domain] Consolidated Entities [Domain] Earnings before income tax expense Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Due in one year or less Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Due after ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Net property, plant and equipment Property, Plant and Equipment, Net Operating and administrative expenses Operating Expenses Other noncurrent liabilities Other Liabilities, Noncurrent Current liabilities: Liabilities, Current [Abstract] Sale of shares to stockholders Stock Issued During Period, Value, New Issues Acquisition of shares from stockholders Treasury Stock, Shares, Acquired Debt Instrument [Line Items] Debt Instrument [Line Items] Investments Marketable Securities Repayment of long-term debt Repayments of Long-term Debt Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Property, plant and equipment Property, Plant and Equipment, Gross Fair value adjustment, due to net unrealized gain, on equity securities held at end of period Equity Securities, FV-NI, Unrealized Gain (Loss) Accounting Policies [Abstract] Accounting Policies [Abstract] Document Quarterly Report Document Quarterly Report Unrealized Loss Position, Accumulated Loss Total, Unrealized Losses Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Total revenues Revenues Sale of shares to stockholders Stock Issued During Period, Shares, New Issues Consolidation Of Joint Ventures And Long Term Debt [Abstract] Consolidation Of Joint Ventures And Long Term Debt [Abstract] Consolidation Of Joint Ventures And Long Term Debt [Abstract] [Abstract] Self-insured claims paid Payments For Self Insured Claims Payments for Self Insured Claims Common stock of $1 par value. Authorized 1,000,000 shares; issued 695,725 shares in 2021 and 690,982 shares in 2020 Common Stock, Value, Issued Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Costs and expenses: Costs and Expenses [Abstract] Common Stock (Acquired from) Sold to Stockholders Treasury Stock, Common [Member] Number of debt securities issues contributing to total unrealized losses Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Long-term debt Long-term Debt, Excluding Current Maturities Basis of Presentation [Policy Text Block] Basis of Accounting, Policy [Policy Text Block] Subsequent Event [Table] Subsequent Event [Table] Accumulated other comprehensive earnings Balances at Beginning of Period Balances at End of Period Accumulated Other Comprehensive Income (Loss), Net of Tax Document Fiscal Period Focus Document Fiscal Period Focus Consolidation Of Joint Ventures And Long Term Debt Disclosure [Text Block] Consolidation Of Joint Ventures And Long Term Debt Disclosure [Text Block] Consolidation of Joint Ventures and Long Term Debt Disclosure. Net amortization of investments Accretion (Amortization) of Discounts and Premiums, Investments Document Documentand Entity Information [Abstract] Document Documentand Entity Information [Abstract] Document Documentand Entity Information [Abstract] Document Period End Date Document Period End Date Investments [Tex Block] Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Total costs and expenses Costs and Expenses Common stock, par value Common Stock, Par or Stated Value Per Share Entity Registrant Name Entity Registrant Name Debt Securities, Available-for-sale, Allowance for Credit Losses Debt Securities, Available-for-sale, Allowance for Credit Loss Treasury stock at cost, shares Treasury Stock, Shares Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Current assets: Assets, Current [Abstract] Other, net Proceeds from (Payments for) Other Financing Activities Entity Central Index Key Entity Central Index Key Unrealized Losses Debt Securities, Available-for-sale, Unrealized Loss Common Stock Related To ESOP Common Stock Related To Esop [Member] Common Stock Related To ESOP [Member] Unrealized gain (loss) on debt securities net of income taxes in 2021 and 2020, respectively. OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Financial Instrument [Axis] Financial Instrument [Axis] Common stock related to Employee Stock Ownership Plan (ESOP) Common stock related to ESOP Temporary Equity, Carrying Amount, Attributable to Parent Common Stock, Dividends, Per Share, Declared Common Stock, Dividends, Per Share, Declared Net other comprehensive earnings (losses) Other Comprehensive Income (Loss), Net of Tax Sales Revenue from Contract with Customer, Excluding Assessed Tax Investment Income, Net [Abstract] Investment Income, Net [Abstract] Cash received from customers Proceeds from Customers Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Dividends paid Payments of Dividends Debt Instrument, Basis Spread on Variable Rate Debt Instrument, Basis Spread on Variable Rate Adjustment to postretirement benefit obligation in 2021 and 2020, respectively. Adjustment to postretirement benefit obligation Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Weighted average shares outstanding Weighted Average Number of Shares Outstanding, Basic and Diluted Equity [Abstract] Equity [Abstract] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Net realized gain on investments Marketable Securities, Realized Gain (Loss) Continuous Unrealized Loss Position, Less than 12 Months, Fair Value Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Common Stock Common Stock [Member] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Changes in operating assets and liabilities providing (requiring) cash: Increase (Decrease) in Operating Capital [Abstract] Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Operating profit Operating Income (Loss) Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Current portion of operating lease liabilities Operating Lease, Liability, Current Due after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Total current liabilities Liabilities, Current Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Retirement contributions paid or payable in common stock Share-based Payment Arrangement, Noncash Expense AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Additional Paid-in Capital Additional Paid-in Capital [Member] Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash and Cash Equivalents, at Carrying Value Reclassification out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Equity Securities [Line Items] Debt and Equity Securities, FV-NI [Line Items] Common Stock, Dividends, Per Share, Cash Paid Common Stock, Dividends, Per Share, Cash Paid Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Contributions to retirement plans Employee Stock Ownership Plan 401 K Payable Current The total amount of the entity's current obligation as of the balance sheet date under its ESOP and 401(k) retirement plans. Document Information [Line Items] Document Information [Line Items] Other nonoperating income (loss), net Other Nonoperating Income (Expense) Statement [Table] Statement [Table] Other liabilities Increase (Decrease) in Other Operating Liabilities Investment Income (Loss) [Table Text Block] Investment Income [Table Text Block] Credit Loss [Abstract] Credit Loss [Abstract] Payment for capital expenditures Payments to Acquire Property, Plant, and Equipment Long-term Debt, Unclassified [Abstract] Long-term Debt, Unclassified [Abstract] Maximum [Member] Maximum [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Reclassification adjustment for net realized gain on debt securities net of income taxes in 2021 and 2020, respectively. Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Total liabilities Liabilities Liabilities Subsequent Event [Member] Subsequent Event [Member] Legal Entity [Axis] Legal Entity [Axis] Dividends Payable, Date Declared Dividends Payable, Date Declared Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Due after ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Dividends and interest received Proceeds from Interest and Dividends Received Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total stockholders’ equity Beginning Balance Ending Balance Stockholders' Equity Attributable to Parent Debt Instrument Maturity Month And Year Debt Instrument Maturity Month And Year Date when the debt instrument maturity is scheduled to be fully repaid, in Month and Year format. Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Common stock, shares issued Common Stock, Shares, Issued Income taxes Accrued Income Taxes, Current Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Adjustments to reconcile net earnings to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Increase in last-in, first-out (LIFO) reserve Inventory, LIFO Reserve, Effect on Income, Net Due in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Postretirement Benefit obligation Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Payment for acquisition of common stock Payments for Repurchase of Common Stock Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Cash paid to employees and suppliers Payments to Suppliers and Employees Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Schedule of Accumulated Other Comprehensive Earnings (Losses) [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Deferred income taxes Deferred Income Tax Expense (Benefit) Inventories Retail Related Inventory, Merchandise Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items] Loss on disposal and impairment of long-lived assets Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal