Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Jul. 31, 2019
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The Consolidated Financial Statements include the accounts of Donaldson Company, Inc. and all of its majority-owned subsidiaries. All intercompany accounts and transactions have been eliminated. The Company’s three joint ventures are not majority-owned and are accounted for under the equity method. Certain reclassifications to previously reported financial information have been made to conform to the current period presentation.
Use of Estimates	Use of Estimates The preparation of the Consolidated Financial Statements in conformity with generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Foreign Currency Translation	Foreign Currency Translation For most foreign operations, local currencies are considered the functional currency. Assets and liabilities of non-U.S. dollar functional currency entities are translated to U.S. dollars at year-end exchange rates and the resulting gains and losses arising from the translation of net assets located outside the U.S. are recorded as a cumulative translation adjustment, a component of accumulated other comprehensive loss in the Consolidated Balance Sheets. Elements of the Consolidated Statements of Earnings are translated at average exchange rates in effect during the year.
Cash Equivalents	Cash Equivalents The Company considers all highly liquid temporary investments with an original maturity of three months or less to be cash equivalents. Cash equivalents are carried at cost that approximates market value.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Trade accounts receivables are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of credit losses in its existing accounts receivable. The Company determines the allowance based on historical write-off experience, regional economic data and evaluation of specific customer accounts for risk of loss. The Company reviews its allowance for doubtful accounts monthly. Past due balances over 90 days and over a specified amount are reviewed individually for collectability. All other balances are reviewed on a pooled basis by reporting unit and geographic region. Account balances are reserved when the Company determines it is probable the receivable will not be recovered.
Inventories	Inventories Inventories are stated at the lower of cost and net realizable value. U.S. inventories are valued using the last-in, first-out (LIFO) method while the non-U.S. inventories are valued using the first-in, first-out (FIFO) method.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost. Additions, improvements or major renewals are capitalized while expenditures that do not enhance or extend the asset’s useful life are charged to expense as incurred. Depreciation is computed using the straight-line method.
Internal-Use Software	Internal-Use Software The Company capitalizes direct costs of materials and services used in the development and purchase of internal-use software. Amounts capitalized are amortized on a straight-line basis over a period of five to seven years and are reported as a component of property, plant and equipment. Cloud Computing Arrangements The Company capitalizes certain costs incurred during the application development stage of implementation of internal use software in cloud computing arrangements. Amounts capitalized are on a straight-line basis over a period of ten years and are reported as a component of other long-term assets.
Goodwill and Other Intangible Assets	Goodwill and Intangible Assets Goodwill represents the excess of the purchase price over the fair value of net assets acquired in business combinations under the purchase method of accounting. Intangible assets, comprised of customer relationships, patents, trademarks and technology, are amortized on a straight-line basis over their estimated useful lives of five to twenty years. Goodwill is assessed for impairment annually or if an event occurs or circumstances change that would indicate the carrying amount may be impaired. The impairment assessment for goodwill is done at a reporting unit level. Reporting units are one level below the operating segment level but can be combined when reporting units within the same operating segment have similar economic characteristics. An impairment loss would be recognized when the carrying amount of the reporting unit’s net assets exceeds the estimated fair value of the reporting unit.
Recoverability of Long-Lived Assets	Recoverability of Long-Lived Assets The Company reviews its long-lived assets, including identifiable intangibles, for impairment when events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If impairment indicators are present and the estimated future undiscounted cash flows are less than the carrying value of the assets, the carrying value is reduced to the fair market value.
Income Taxes	Income Taxes The provision for income taxes is computed based on the pretax income reported for financial statement purposes. Deferred tax assets and liabilities are recognized for the expected future tax consequences attributed to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are anticipated to reverse. Valuation allowances are recorded to reduce deferred tax assets when it is more-likely-than-not that a tax benefit will not be realized. The Company maintains a reserve for uncertain tax benefits. Benefits of tax return positions are recognized in the financial statements when the position is “more-likely-than-not” to be sustained by the taxing authorities based solely on the technical merits of the position. If the recognition threshold is met, the tax benefit is measured and recognized as the largest amount of tax benefit that in the Company’s judgment is greater than 50% likely to be realized.
Treasury Stock	Treasury Stock Repurchased common stock is stated at cost (determined on an average cost basis) and is presented as a reduction of shareholders’ equity.
Research and Development Expense	Research and Development Expense Research and development expenses include basic scientific research and the application of scientific advances to the development of new and improved products and their uses and are charged against earnings in the year incurred.
Stock-Based Compensation	Stock-Based Compensation The Company offers stock-based employee compensation plans, which are more fully described in Note 10. Stock-based employee compensation expense is recognized using the fair-value method for all awards.
Revenue Recognition	Revenue Recognition Revenue is measured as the amount of consideration the Company expects to receive in exchange for the fulfillment of performance obligations. The transaction price of a contract could be reduced by variable consideration including product refunds, returns, volume rebates and discounts in the determination of net sales. The Company primarily relies on historical experience and anticipated future performance to estimate the variable consideration. Revenue is recognized to the extent that it is probable that a significant reversal of revenue will not occur when outstanding contingencies are resolved. The Company also accounts for amounts billed to customers for reimbursement of shipping and handling as fulfillment costs by recording these amounts as revenue and accruing the costs when the related revenue is recognized. For most customer contracts, the Company recognizes revenue at a point in time when control of the goods or services is transferred to the customer. For product sales, control is typically deemed to have transferred in accordance with the shipping terms, either at the time of shipment from the plants or distribution centers or the time of delivery to the customers. Revenue is recognized for services upon completion of those services. Due to the customized nature of some of the Company’s products, together with contractual provisions in certain customer contracts that provide the Company with an enforceable right to payment of the transaction price for performance completed to date, revenue is recognized for these contracts over time. For these contracts, the Company recognizes revenue on products by an output measure of production, which fairly depicts the amount of revenue the Company is entitled to. The timing of revenue recognized from these products is slightly accelerated compared to revenue recognized at the point in time of shipment or delivery. Incremental costs of obtaining a contract with a customer and other costs to fulfill a contract are required to be capitalized unless the Company elects to expense contract costs with periods less than a year. The Company has elected to expense these costs of obtaining a contract as incurred when the related contract period is less than one year. The Company does not pay upfront sales commissions on contracts when the related contract period is greater than one year, thus has not capitalized any amounts as of July 31, 2019, see Note 6.
Product Warranties	Product Warranties The Company provides for estimated warranty expense at the time of sale and accrues for specific items at the time their existence is known and the amounts are determinable. The Company estimates warranty expense using quantitative measures based on historical warranty claim experience and evaluation of specific customer warranty issues.
Forward Foreign Currency Contracts and Net Investment Hedges	Forward Foreign Currency Contracts The Company uses forward currency exchange contracts to manage exposure to fluctuations in foreign currency. The Company enters into certain purchase commitments with foreign suppliers based on the value of its purchasing subsidiaries’ local currency relative to the currency requirement of the supplier on the date of the commitment. The Company also sells into foreign countries based on the value of the purchaser’s local currency. The Company mitigates risk through using forward currency contracts that generally mature in 12 months or less, which is consistent with the related purchases and sales. Contracts that qualify for hedge accounting are designated as cash flow hedges. See Note 13. Net Investment Hedges The Company uses fixed-to-fixed cross currency swap agreements to hedge its exposure to adverse foreign currency exchange rate movements for its operations in Europe.
New Accounting Standards Recently Adopted	New Accounting Standards Recently Adopted In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (ASC 606), which amended revenue recognition guidance to clarify the principles for recognizing revenue from contracts with customers. The guidance requires an entity to recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which an entity expects to be entitled in exchange for those goods or services. The guidance also requires expanded disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Additionally, qualitative and quantitative disclosures are required about customer contracts, significant judgments and changes in judgments and assets recognized from the costs to obtain or fulfill a contract. In 2016, the FASB issued ASU 2016-08, ASU 2016-10, ASU 2016-11, ASU 2016-12 and ASU 2016-20 to clarify, among other things, the implementation guidance related to principal versus agent considerations, identifying performance obligations and accounting for licenses of intellectual property. This accounting guidance was effective for the Company beginning in the first quarter of fiscal 2019. The standard was adopted using the modified retrospective method, applying the guidance to those contracts which were not completed as of July 31, 2018, with the cumulative effect of adoption recognized during the first quarter. Refer to Note 6 for the impact of the adoption of this new standard. In January 2017, the FASB issued ASU 2017-01, Business Combinations: Clarifying the Definition of a Business (ASU 2017-01). The new guidance provides a more robust framework to use in determining when a set of assets and activities is a business. The amendments provide more consistency in applying the guidance, reduce the costs of application and make the definition of a business more operable. ASU 2017-01 was effective for the Company beginning in the first quarter of fiscal 2019. The Company adopted ASU 2017-01 in the first quarter of fiscal 2019 and it did not have a material impact on its Consolidated Financial Statements. In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits (Topic 715) (ASU 2017-07). The new guidance requires employers to disaggregate and present separately the current service cost component from the other components of net benefit cost within the consolidated statement of earnings. ASU 2017-07 was effective for the Company beginning in the first quarter of fiscal 2019. The Company adopted ASU 2017-07 in the first quarter of fiscal 2019 using the retrospective method. This resulted in a reclassification of net benefit costs in the Consolidated Statements of Earnings, with a decrease in other income, net of $3.0 million and $5.0 million for the years ended July 31, 2018 and 2017, respectively, offset in selling, general and administrative and cost of goods sold. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities (ASU 2017-12), which improves the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements and make certain targeted improvements to simplify the application of the hedge accounting guidance. The guidance expands the ability to hedge non-financial and financial risk components, reduces complexity in fair value hedges of interest rate risk, eliminates the requirement to separately measure and report hedge ineffectiveness and eases certain hedge effectiveness assessment requirements. ASU 2017-12 is effective for the Company beginning in the first quarter of fiscal 2020, and early adoption is permitted. The Company adopted ASU 2017-12 in the first quarter of fiscal 2019 and it did not have a material impact on its Consolidated Financial Statements. In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (ASU 2018-15). The amendments in this update align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by the amendments in this update. The amendments in this update are effective for interim and annual periods for the Company beginning in the first quarter of fiscal 2021, with early adoption permitted. The amendments in this update should be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company adopted ASU 2018-15, on a prospective basis, in the third quarter of fiscal 2019 and it did not have a material impact on its Consolidated Financial Statements. New Accounting Standards Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (ASU 2016-02), which requires lessees to recognize right-of-use assets and lease liabilities for substantially all leases. This accounting guidance is effective for the Company beginning in the first quarter of fiscal 2020 on a modified retrospective basis. The Company will prospectively adopt ASU 2016-02 in the first quarter of fiscal 2020, recognizing new right of use assets and lease liabilities for all operating leases on its Consolidated Balance Sheets, with the exception of leases with a noncancelable term of 12 months or less. Upon adoption, the Company estimates both assets and liabilities on its Consolidated Balance Sheets will increase by approximately $65 million to $75 million, which includes the effect of discounting. Changes in the Company’s lease population may impact this estimate. The Company will expand its consolidated financial statement disclosures upon adoption of this standard. In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments (ASU 2016-13). In November 2018, the FASB issued update ASU 2018-19 that clarifies the scope of the standard in the amendments in ASU 2016-13. This guidance introduces a new model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses. Financial instruments impacted include accounts receivable, trade receivables, other financial assets measured at amortized cost and other off-balance sheet credit exposures. The new guidance is effective for the Company beginning in the first quarter of fiscal 2021, with early adoption permitted. The Company is evaluating the impact of the adoption of ASU 2016-13 on its Consolidated Financial Statements. In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (ASU 2018-02). The guidance allows a company to elect to reclassify from accumulated other comprehensive income (AOCI) to retained earnings the stranded tax effects from the adoption of the newly enacted federal corporate tax rate as a result of the U.S. Tax Cuts and Jobs Act. The amount of the reclassification is calculated as the difference between the amount initially charged to other comprehensive income (OCI) at the previously enacted tax rate that remains in AOCI and the amount that would have been charged using the newly enacted tax rate, excluding any valuation allowance previously charged to income. The new guidance is effective for the Company beginning in the first quarter of fiscal 2020, and early adoption is permitted. The Company is evaluating the impact of the adoption of ASU 2018-02 on its Consolidated Financial Statements. In April 2019, the FASB issues ASU 2019-04, Codification Improvements to Topics 326, Financial Instruments - Credit Losses, Topic 815 Derivatives and Hedging and Topic 825, Financial Instruments (ASU 2019-04). This guidance clarifies areas of guidance related to the recently issued standards on credit losses (Topic 326), derivatives and hedging (Topic 815), and recognition and measurement of financial instruments (Topic 825). The new guidance is effective for the Company beginning in the first quarter of fiscal 2021. The Company is evaluating the impact of the adoption of ASU 2019-04 on its Consolidated Financial Statements.
Earnings Per Share	The Company’s basic net earnings per share is computed by dividing net earnings by the weighted average number of outstanding common shares. The Company’s diluted net earnings per share is computed by dividing net earnings by the weighted average number of outstanding common shares and common share equivalents related to stock options and stock incentive plans. Certain outstanding options are excluded from the diluted net earnings per share calculations because their exercise prices are greater than the average market price of the Company’s common stock during those periods.