Share-based Payment Arrangement [Abstract] Schedule of Restricted Stock Transactions Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] Inventory Disclosure [Abstract] Inventory, Current [Table] Inventory, Current [Table] Inventory [Axis] Inventory [Axis] Inventory [Domain] Inventory [Domain] Inventory Inventory [Line Items] Finished goods Inventory, Finished Goods, Gross Packaging Packaging Inventory Packaging Inventory Other Other Inventory, Gross Total Inventories Inventory, Net Income Tax Disclosure [Abstract] CARES Act, Current Payroll Tax Deferral CARES Act, Current Payroll Tax Deferral On March 27, 2020, in response to the COVID-19 pandemic, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was signed into U.S. law. The CARES Act provides for, among other things, deferral of the employer portion of social security taxes incurred through the end of calendar 2020. CARES Act, Future Payroll Tax Deferral CARES Act, Future Payroll Tax Deferral On March 27, 2020, in response to the COVID-19 pandemic, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was signed into U.S. law. The CARES Act provides for, among other things, deferral of the employer portion of social security taxes incurred through the end of calendar 2020. Leases [Abstract] Lessee, Operating Leases Lessee, Operating Leases [Text Block] Fair Value Disclosures [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Measurement [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Cash Equivalents Cash Equivalents, at Carrying Value Notes Payable, Fair Value Long-term Debt, Fair Value Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2006 Plan 2006 Plan [Member] 2006 Plan [Member] Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] Restricted Stock Restricted Stock [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Stock Common Stock [Member] Common Class B Common Class B [Member] Share-based Compensation Arrangement by Share-based Payment Award Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Number Authorized (shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Award Vesting Period, Minimum (years) ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodMinimum Mininimum period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition Award Vesting Period, Maximum (years) ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodMaximum Maximum period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition Granted, number of shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Share-based Compensation Expense Share-based Payment Arrangement, Expense Inventories Inventory Disclosure [Text Block] Defined Benefit Plan [Abstract] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement 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] Postretirement Health Plan Other Postretirement Benefits Plan [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of Prior service costs Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of Other actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Consolidated Statements of Stockholders' Equity [Abstract] Consolidated Statements of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Total Stockholders' Equity Equity Component [Domain] Common & Class B Stock Additional Paid-in Capital Additional Paid-in Capital [Member] Retained Earnings Retained Earnings [Member] Treasury Stock Treasury Stock, Common [Member] Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Noncontrolling Interest Noncontrolling Interest [Member] Statement Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Total, Beginning of Period Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Common & Class B Stock, Beginning of Period (in shares) Common Stock, Shares, Outstanding Treasury Stock, Beginning of Period (in shares) Treasury Stock, Common, Shares Net Income Attributable to Oil-Dri Net Income (Loss) Attributable to Parent Net Income (Loss) Attributable to Noncontrolling Interest Net Income (Loss) Attributable to Noncontrolling Interest Net Income, Including Portion Attributable to Noncontrolling Interest Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive income Other Comprehensive Income (Loss), Net of Tax Dividends declared Dividends, Common Stock, Cash Purchases of treasury stock Treasury Stock, Value, Acquired, Cost Method Purchases of treasury stock (in shares) Treasury Stock, Shares, Acquired Net issuance of stock under long-term incentive plans Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Net issuance of stock under long-term incentive plans (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Amortization of restricted stock APIC, Share-based Payment Arrangement, Increase for Cost Recognition Contributions from noncontrolling interests Proceeds from Noncontrolling Interests Total, End of Period Common Stock & Class B Stock, End of Period (in shares) Treasury Stock, End of Period (in shares) Noncontrolling Interest Items [Abstract] Noncontrolling Interest Items [Abstract] Noncontrolling Interest [Table] Noncontrolling Interest [Table] Ownership [Axis] Ownership [Axis] Ownership Ownership [Domain] Noncontrolling Interest Noncontrolling Interest Agromex [Member] Noncontrolling Interest Agromex [Member] Parent Parent Oil-Dri Corporation of America [Member] Parent Oil-Dri Corporation of America [Member] Noncontrolling Interest Noncontrolling Interest [Line Items] Noncontrolling Interest, Parent Ownership Percentage Prior to Purchase of Additional Interest Noncontrolling Interest, Parent Ownership Percentage Prior to Purchase of Additional Interest The parent entity's interest in net assets of the subsidiary, expressed as a percentage prior to the purchase of additional interest Noncontrolling Interest, Ownership Percentage by Parent Noncontrolling Interest, Ownership Percentage by Parent Amount Contributed to Purchase of Additional Interest by Parent Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent Noncontrolling Interest, Ownership Percentage Prior to Parent's Purchase of Additional Interest Noncontrolling Interest Ownership Percentage Prior to Parent's Purchase of Additional Interest The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity. prior to purchase of additional interest by Parent Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Series A Senior Note Senior Notes [Member] Series B Senior Note Series B Senior Note [Member] The name for series B debt instrument or borrowing that distinguishes it from other debt instruments or borrowings, including draws against credit facilities. Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Amended Note Agreement Subsequent Event [Member] License Payment License Payment [Member] Payment received in fourth quarter of fiscal year 2020 for the use of license Pension Pension Benefits [Member] Expense related to lump sum buyout election for our terminated and vested participants in connection with the freeze of our Pension. Subsequent Event Subsequent Event [Line Items] Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Maturity Date Debt Instrument, Maturity Date Debt Instrument, Face Amount Debt Instrument, Face Amount Debt Instrument, Annual Principal Payment Senior Notes, Current Senior Note, Maximum Borrowing Capacity Senior note, Maximum Borrowing Capacity Amount of maximum borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date. Proceeds from License to be Received Proceeds from License to be Received Cash to be received from the grant of a non-exclusive, perpetual license to develop, manufacture, use, distribute and sell products produced using formulations under certain of our patents. Lump Sum Payment for Pension Benefits Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Goodwill and Intangible Assets Disclosure [Abstract] 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] Finite-Lived Intangible Assets, Future Amortization Expense Finite-Lived Intangible Assets [Line Items] 2021 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2024 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2025 Finite-Lived Intangible Assets, Amortization Expense, Year Five Pension and Other Postretirement Benefits Disclosure Pension and Other Postretirement Benefits Disclosure [Text Block] Inventories Schedule of Inventory, Current [Table Text Block] Condensed Consolidated Balance Sheet Parenthetical [Abstract] Condensed Consolidated Balance Sheet Parenthetical [Abstract] Current Assets Assets, Current [Abstract] Allowance for doubtful accounts Accounts Receivable, Allowance for Credit Loss, Current Other Assets Other Assets, Noncurrent [Abstract] Accumulated amortization of other intangibles TrademarksAndPatentsAccumulated Amortization The accumulated amount of amortization of the costs pertaining to the rights acquired through registration of a trademark to gain or protect exclusive use of a business name, symbol or other device or style for a projected indefinite period of benefit PLUS the accumulated amount of amortization of the costs pertaining to the exclusive legal rights granted to the owner of the patent to exploit an invention or a process for a period of time specified by law. Accumulated amortization of customer lists Customer list accumulated amortization Accumulated amortization as of the balance sheet date that pertains to a customer list finite-lived intangible asset. Current Liabilities Liabilities, Current [Abstract] Net unamortized debt issuance costs Debt Issuance Costs, Current, Net Noncurrent Liabilities Liabilities, Noncurrent [Abstract] Net unamortized debt issuance costs Debt Issuance Costs, Noncurrent, Net Stockholder's Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares issued Common Stock, Shares, Issued Treasury stock, common shares Treasury Stock, Shares Fair Value Measurements Fair Value Disclosures [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Trade Receivables Accounts Receivable [Policy Text Block] Overburden Removal and Mining Costs Overburden Removal and Mining Costs [Policy Text Block] Description of accounting policy for overburden removal/stripping costs for mined properties and other mining-related costs. Reclamation Asset Retirement Obligation [Policy Text Block] Leases Lessee, Leases [Policy Text Block] Revenue Recognition Revenue [Policy Text Block] Selling, General and Administrative Expenses Selling, General and Administrative Expenses, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Finite-Lived Intangible Assets Amortization of intangible assets Amortization of Intangible Assets Amortization expense for remainder of current fiscal year Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Indefinite-lived trademarks Indefinite-lived Intangible Assets (Excluding Goodwill) Goodwill impairment loss Goodwill, Impairment Loss Discount rate for net periodic benefit cost Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Rate of increase in compensation levels Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Long-term expected rate of return on assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Statement of Cash Flows [Abstract] Statement, Scenario [Axis] Scenario [Axis] Scenario [Domain] Scenario [Domain] CASH FLOWS FROM OPERATING ACTIVITIES Net Cash Provided by (Used in) Operating Activities [Abstract] Net Income Adjustments to reconcile net 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, Amortization and Accretion, Net Amortization of investment net discount Accretion (Amortization) of Discounts and Premiums, Investments Stock-based compensation Share-based Payment Arrangement, Noncash Expense Deferred income taxes Deferred Income Tax Expense (Benefit) Provision for bad debts and cash discounts Accounts Receivable, Credit Loss Expense (Reversal) Loss on the sale of fixed assets Gain (Loss) on Disposition of Property Plant Equipment Curtailment gain on SERP Plan Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment (Increase) Decrease in assets: Increase (Decrease) in Operating Assets [Abstract] Accounts receivable Increase (Decrease) in Accounts and Other Receivables Inventories Increase (Decrease) in Inventories Prepaid expenses Increase (Decrease) in Prepaid Expense and Other Assets Other assets Increase (Decrease) in Other Operating Assets Increase (Decrease) in liabilities: Increase (Decrease) in Operating Liabilities [Abstract] Accounts payable Increase (Decrease) in Accounts Payable and Income Taxes Payable The increase (decrease) during the reporting period in the aggregate amount of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business PLUS the increase (decrease) during the period in the amount due for taxes based on the reporting entity's earnings or attributable to the entity's income earning process (business presence) within a given jurisdiction. Accrued expenses Increase (Decrease) in Accrued Liabilities Deferred compensation Increase (Decrease) in Deferred Compensation Pension and postretirement benefits Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits Other liabilities Increase (Decrease) in Other Operating Liabilities Total Adjustments Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Net Cash Provided by Operating Activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Proceeds from Sale of Property, Plant, and Equipment Proceeds from Sale of Property, Plant, and Equipment Purchases of short-term investments Payments to Acquire Short-term Investments Dispositions of short-term investments Proceeds from Sale of Short-term Investments Net Cash Used in Investing Activities Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES Net Cash Provided by (Used in) Financing Activities [Abstract] Principal payments on notes payable Repayments of Senior Debt Dividends paid Payments of Ordinary Dividends, Common Stock Purchase of treasury stock Payments for Repurchase of Common Stock Contributions from noncontrolling interests Proceeds from (Payments to) Noncontrolling Interests Net Cash Used in Financing Activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on Cash and Cash Equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net (Decrease) Increase 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, Beginning of Period Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents, End of Period Supplemental disclosure of non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Capital expenditures accrued, but not paid Capital Expenditures Incurred but Not yet Paid Cash dividends declared and accrued, but not paid Dividends Payable Postretirement Health Plan Supplemental Executive Retirement Plan Supplemental Employee Retirement Plan [Member] Pension Plan Obligation Decrease for Curtailment Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax Voluntary contributions Defined Benefit Plan Voluntary Contribution Defined Benefit Plan Voluntary Contribution Estimated contributions in remainder of current fiscal year Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year Medical Cost Trend Assumption Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Ultimate Health Care Cost Trend Rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Year that Rate Reaches Ultimate Trend Rate Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Non-vested restricted stock outstanding, beginning balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Vested, number of shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeitures, number of shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Non-vested restricted stock outstanding, ending balance Non-vested restricted stock outstanding, weighted average grant date fair value, beginning balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted, weighted average grant date fair value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Vested, weighted average grant date fair value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Forfeitures, weighted average grant date fair value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Non-vested restricted stock outstanding, weighted average grant date fair value, ending balance Lease cost Lease, Cost [Table Text Block] Operating lease payments due within next twelve months as of April 30, Lessee, Operating Lease, Liability, Maturity [Table Text Block] Operating lease payments due within next twelve months as of July 31, 2019 Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Schedule of Assumptions Used Defined Benefit Plan, Assumptions [Table Text Block] Accumulated Other Comprehensive Income [Abstract] Accumulated Other Comprehensive Income [Abstract] Accumulated Other Comprehensive (Loss) Income by Component Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Related Party Transactions [Abstract] Related Party Transactions Disclosure Related Party Transactions Disclosure [Text Block] Condensed Consolidated Statements of Income and Retained Earnings [Abstract] Condensed Consolidated Statements of Income and Retained Earnings [Abstract] Net Sales Revenue from Contract with Customer, Excluding Assessed Tax Cost of Sales Cost of Goods and Services Sold Gross Profit Gross Profit Selling, General and Administrative Expenses Selling, General and Administrative Expense Income from Operations Operating Income (Loss) Other (Expense) Income Nonoperating Income (Expense) [Abstract] Interest expense Interest Expense, Debt Interest income Investment Income, Interest Other, net Other Nonoperating Income (Expense) Total Other (Expense) Income, Net Nonoperating Income (Expense) Income Before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income Tax Expense Income Tax Expense (Benefit) Net Income Net Income Attributable to Oil-Dri Net Income Per Share Earnings Per Share [Abstract] Basic Common (in dollars per share) Earnings Per Share, Basic Diluted Common (in dollars per share) Earnings Per Share, Diluted Average Shares Outstanding Weighted Average Shares Outstanding [Abstract] Weighted Average Shares Outstanding [Abstract] Basic Common (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted Common (in shares) Weighted Average Number of Shares Outstanding, Diluted Dividends Declared Per Share (in dollars per share) Common Stock, Dividends, Per Share, Declared Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Axis] Segment [Domain] Segments [Domain] Business to Business Products Business to Business Segment [Member] Business to Business Segment [Member] Retail and Wholesale Products Retail and Wholesale Segment [Member] Retail and Wholesale Segment [Member] Unallocated Assets Segment Reconciling Items [Member] Segment Reporting Information Segment Reporting Information [Line Items] Assets Assets Segment Income Segment Reporting Information, Operating Income for Reportable Segment Segment Reporting Information, Operating Income for Reportable Segment Corporate Expenses Corporate Expenses The corporate expenses line represents certain unallocated expenses, including primarily salaries, wages and benefits, purchased services, rent, utilities and depreciation and amortization associated with corporate functions such as research and development, information systems, finance, legal, human resources and customer service. Corporate expenses also include the annual incentive plan bonus accrual. Income from Operations Total Other (Expense) Income, Net Income before Income Taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income Tax Expense Revenue from Contract with Customer [Abstract] Revenue by Principal Product by Operating Segment [Table] Disaggregation of Revenue [Table] Product and Service [Axis] Product and Service [Axis] Prinicipal Products [Domain] Product and Service [Domain] Cat Litter Cat Litter [Member] Information about principal product: Cat Litter [Member] Industrial and Sports Industrial and Sports [Member] Information about principal product: Industrial and Sports [Member] Agricultural and Horticultural Agricultural and Horticultural [Member] Information about principal product: Agricultural and Horticultural [Member] Bleaching Clay and Fluids Purification Bleaching Clay and Fluids Purification [Member] Information about principal product: Bleaching Clay and Fluids Purification [Member] Animal Health and Nutrition Animal Health and Nutrition [Member] Information about principal product: Animal Health and Nutrition [Member] Revenue by Principal Product Disaggregation of Revenue [Line Items] Lease, Cost Lease, Cost [Abstract] Operating lease cost Operating Lease, Cost Short-term operating lease cost Short-term Lease, Cost Operating cash flows from operating leases Operating Lease, Payments Weighted-average remaining lease term - operating leaes Operating Lease, Weighted Average Remaining Lease Term Weighted-average discount rate - operating leases Operating Lease, Weighted Average Discount Rate, Percent Lessee, Operating Lease, Liability, Payment, Due, Rolling Maturity Lessee, Operating Lease, Liability, Payment, Due, Rolling Maturity [Abstract] 2020 Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months 2021 Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Two 2022 Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Three 2023 Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Four 2024 Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Five Thereafter Lessee, Operating Lease, Liability, Payments, Due after Rolling Year Five Total Lessee, Operating Lease, Liability, Payments, Due Less: imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Net lease obligation Operating Lease, Liability Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2020 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2021 Operating Leases, Future Minimum Payments, Due in Two Years 2022 Operating Leases, Future Minimum Payments, Due in Three Years 2023 Operating Leases, Future Minimum Payments, Due in Four Years 2024 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Fair Value Measurement, Policy Fair Value Measurement, Policy [Policy Text Block] Revenue Recognition [Abstract] Deferred Revenue Arrangement, by Type [Table] Deferred Revenue Arrangement, by Type [Table] Deferred Revenue Arrangement Type [Axis] Deferred Revenue Arrangement Type [Axis] Deferred Revenue Deferred Revenue [Domain] Payments In Advance Up-front Payment Arrangement [Member] Deferred Revenue Arrangement Deferred Revenue Arrangement [Line Items] Liability for Payments in Advance Deferred Revenue, Current Payments in Advance, Revenue Recognized Deferred Revenue, Revenue Recognized Operating Segments Segment Reporting, Policy [Policy Text Block] NEW ACCOUNTING PRONOUNCEMENTS [Abstract] NEW ACCOUNTING PRONOUNCEMENTS [Abstract] New Accounting Pronouncements New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Total Accumulated Other Comprehensive (Loss) Income Pension and Postretirement Health Benefits Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Cumulative Translation Adjustment Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Accumulated Other Comprehensive (Loss) Income Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive (Loss) Income, Balance, beginning Accumulated Other Comprehensive Income (Loss), Net of Tax Other comprehensive loss before reclassifications, net of tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Amounts reclassified from accumulated other comprehensive income, net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Curtailment on Pension Plan Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax Net current-period other comprehensive income (loss), net of tax Accumulated Other Comprehensive (Loss) Income, Balance, ending Number of Reportable Segments Number of Reportable Segments Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Director Director [Member] Related Party Transaction Related Party Transaction [Line Items] Net sales to related party Revenue from Related Parties Current Fiscal Year End Date Current Fiscal Year End Date Accounts receivable from related party Accounts Receivable, Related Parties, Current Document Period End Date Document Period End Date Payments to related party Related Party Transaction, Purchases from Related Party Accounts payable to related party Accounts Payable, Related Parties, Current Basis of Statement Presentation Basis of Presentation and Significant Accounting Policies [Text Block] Cover [Abstract] Entities [Table] Entities [Table] Entity Information Entity Information [Line Items] Document Type Document Type Document Quarterly Report Document Quarterly Report 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 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, Address Line Two Entity Address, Address Line Two Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Address, State or Province Entity Address, State or Province Entity Address, City or Town Entity Address, City or Town City Area Code City Area Code Local Phone Number Local Phone Number 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 Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] ASC 842 Leases Accounting Standards Update 2016-02 [Member] New Accounting Pronouncements or Change in Accounting Principle New Accounting Pronouncements or Change in Accounting Principle [Line Items] Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents Accounts receivable, less allowance of $1,324 and $644 at April 30, 2020 and July 31, 2019, respectively Receivables, Net, Current Inventories Prepaid repairs expense Prepaid repairs expense Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date for elements of machinery or equipment held for the purpose of replacing similar parts in the course of repair or maintenance. Prepaid repairs expense Other Prepaid Expense, Current Total Current Assets Assets, Current Property, Plant and Equipment Property, Plant and Equipment, Net [Abstract] Cost Property, Plant and Equipment, Gross Less accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total Property, Plant and Equipment, Net Property, Plant and Equipment, Net Goodwill Goodwill Other intangibles, net of accumulated amortization of $415 and $299 at April 30, 2020 and July 31, 2019, respectively Trademarks and patents, net The total amount, net of amortization, as of the balance sheet date for 1) the rights acquired through registration of a trademark to gain or protect exclusive use of a business name, symbol or other device or style for a projected indefinite period of benefit and 2) costs pertaining to the exclusive legal rights granted to the owner of the patent to exploit an invention or a process for a period of time specified by law. Customer list, net of accumulated amortization of $6,739 and $6,297 at April 30, 2020 and July 31, 2019, respectively Customer list, net Gross carrying amount before accumulated amortization as of the balance sheet date of an asset comprised of customer information, acquired in a business combination or other transaction, having a finite beneficial life. Deferred Income Tax Assets, Net Deferred Income Tax Assets, Net Other Other Assets, Noncurrent Total Other Assets Assets, Noncurrent Total Assets LIABILITIES & STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current maturities of notes payable, net of unamortized debt issuance costs of $10 at April 30, 2020 Accounts Payable, Current Accounts Payable, Current Dividends payable Dividends Payable, Current Operating lease liabilities Operating Lease, Liability, Current Accrued expenses: Accrued Liabilities, Current [Abstract] Salaries, wages and commissions Employee-related Liabilities, Current Trade promotions and advertising Accrued Marketing Costs, Current Freight Accrued Liabilities, Current Other Other Liabilities, Current Total Current Liabilities Liabilities, Current Notes payable, net of unamortized debt issuance costs of $31 at July 31, 2019 Senior Notes, Noncurrent Deferred compensation Deferred Compensation Liability, Classified, Noncurrent Pension and postretirement benefits Liability, Defined Benefit Plan, Noncurrent Long-term operating lease liabilities Operating Lease, Liability, Noncurrent Other Other Liabilities, Noncurrent Total Noncurrent Liabilities Liabilities, Noncurrent Total Liabilities Liabilities Stockholders’ Equity Common Stock, Value, Issued Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Accumulated Other Comprehensive Loss: Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Pension and postretirement benefits Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Cumulative translation adjustment Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Total Accumulated Other Comprehensive Loss Less Treasury Stock, at cost (3,063,813 Common and 335,816 Class B shares at April 30, 2020 and 2,926,547 Common and 324,741 Class B shares at July 31, 2019) Treasury Stock, Value Total Stockholders' Equity Total Liabilities & Stockholders’ Equity Liabilities and Equity Revenue by Principal Product by Operating Segment Disaggregation of Revenue [Table Text Block] Operating Segments Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Condensed Consolidated Statements of Comprehensive Income [Abstract] Condensed Consolidated Statements of Comprehensive Income [Abstract] Other Comprehensive Income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Pension and postretirement benefits (net of tax) Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Cumulative translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Other Comprehensive Income Total Comprehensive Income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Tax for reclassification adjustment from AOCI for pension and other postretirement benefits Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax Operating Segment Disclosure Segment Reporting Disclosure [Text Block] Disclosure of Compensation Related Costs, Share-based Payments Share-based Payment Arrangement [Text Block] Inventory obsolescence reserve Inventory Valuation Reserves Subsequent Events [Text Block] Subsequent Events [Text Block] Inventories Inventory, Policy [Policy Text Block] Accumulated Other Comprehensive (Loss) Income Comprehensive Income (Loss) Note [Text Block]