Summary of Significant Accounting Policies (Policies)	9 Months Ended
Apr. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements of Donaldson Company, Inc. and its subsidiaries (the Company) have been prepared in accordance with generally accepted accounting principles in the United States (GAAP) and the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and notes required for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair statement of earnings, comprehensive income, financial position and cash flows have been included and are of a normal recurring nature. Operating results for the three and nine month periods ended April 30, 2018 are not necessarily indicative of the results that may be expected for future periods. The year-end condensed consolidated balance sheet information was derived from the Company's audited financial statements but does not include all disclosures required by GAAP. For further information, refer to the Audited Consolidated Financial Statements and Notes thereto included in the Company’s Annual Report on Form 10-K for the year ended July 31, 2017.
New Accounting Standards Recently Adopted and New Accounting Standards Not Yet Adopted	New Accounting Standards Recently Adopted In July 2015, the FASB issued Accounting Standards Update (ASU) 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory (ASU 2015-11), which amended the guidance requiring companies not using the last-in, first-out (LIFO) method to measure inventory at the lower of cost and net realizable value rather than the lower of cost or market. This accounting guidance was effective for the Company beginning in the first quarter of fiscal 2018 and did not have an impact on its Consolidated Financial Statements. In March 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). This update simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 was effective for the Company beginning in the first quarter of fiscal 2018 and the guidance affecting the effective tax rate was adopted prospectively. The Condensed Consolidated Statements of Cash Flows is also presented retrospectively with the guidance of this new standard and, for the nine months ended April 30, 2017, resulted in an increase of $6.7 million to net cash provided by operating activities and a corresponding $6.7 million increase to net cash used in financing activities. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230) (ASU 2016-15). The new guidance is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. ASU 2016-15 is effective for the Company beginning in the first quarter of fiscal 2019. Early adoption is permitted, provided that all of the amendments are adopted in the same period. The guidance requires application using a retrospective transition method. The Company adopted ASU 2016-15 in the first quarter of fiscal 2018 and it did not have an impact on its Consolidated Financial Statements. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (ASU 2016-16), which is intended to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. This update removes the current exception in GAAP prohibiting entities from recognizing current and deferred income tax expenses or benefits related to transfer of assets, other than inventory, within the consolidated entity. The current exception to defer the recognition of any tax impact on the transfer of inventory within the consolidated entity until it is sold to a third party remains unaffected. ASU 2016-16 is effective for the Company beginning in the first quarter of fiscal 2019 and early adoption is permitted. The Company adopted ASU 2016-16 in the first quarter of fiscal 2018 and it did not have an impact on its Consolidated Financial Statements. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718) (ASU 2017-09). The amendments in ASU 2017-09 provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. ASU 2017-09 is effective for the Company beginning in the first quarter of fiscal 2019 and early adoption is permitted. The Company adopted ASU 2017-09 in the first quarter of fiscal 2018 and it did not have an impact on its Consolidated Financial Statements. New Accounting Standards Not Yet Adopted In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09), 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 is effective for the Company beginning in the first quarter of fiscal 2019. The amendments in this update are to be applied on a retrospective basis, either to each prior reporting period presented (full retrospective method) or by presenting the cumulative effect of applying the update recognized at the date of initial application (modified retrospective method). The Company is evaluating the impact of the adoption of the standard on its Consolidated Financial Statements. A project team has been established, has conducted surveys of the businesses, is performing revenue contract analyses to gather information and identify where potential differences could result in applying the requirements of the new standard and has begun assessing the financial impact of the new standard on its Consolidated Financial Statements. The results of this assessment have not yet been determined. During the quarter ended April 30, 2018, the Company made the decision that it anticipates adopting the standard using the modified retrospective method, applying the guidance to those contracts which were not completed as of August 1, 2018. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (ASU 2016-02), which amends the guidance requiring companies to recognize assets and liabilities for leases with lease terms of more than twelve months. The new guidance will require companies to record both capital and operating leases on the balance sheet. This accounting guidance is effective for the Company beginning in the first quarter of fiscal 2020 on a modified retrospective basis, and early adoption is permitted. The Company is evaluating the impact of the adoption of ASU 2016-02 on its Consolidated Financial Statements. 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 is effective for the Company beginning in the first quarter of fiscal 2019. The Company does not expect the application of ASU 2017-01 will 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 is effective for the Company beginning in the first quarter of fiscal 2019. The Company is evaluating the impact of the adoption of ASU 2017-07 on its Consolidated Statements of Earnings. 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, as well as 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 is evaluating the impact of the adoption of ASU 2017-12 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 time of 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. ASU 2018-02 is effective for the Company beginning in the first quarter of fiscal 2020, and early adoption is permitted.

New Accounting Standards Recently Adopted In July 2015, the FASB issued Accounting Standards Update (ASU) 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory (ASU 2015-11), which amended the guidance requiring companies not using the last-in, first-out (LIFO) method to measure inventory at the lower of cost and net realizable value rather than the lower of cost or market. This accounting guidance was effective for the Company beginning in the first quarter of fiscal 2018 and did not have an impact on its Consolidated Financial Statements.

In March 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). This update simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 was effective for the Company beginning in the first quarter of fiscal 2018 and the guidance affecting the effective tax rate was adopted prospectively. The Condensed Consolidated Statements of Cash Flows is also presented retrospectively with the guidance of this new standard and, for the nine months ended April 30, 2017, resulted in an increase of $6.7 million to net cash provided by operating activities and a corresponding $6.7 million increase to net cash used in financing activities.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230) (ASU 2016-15). The new guidance is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. ASU 2016-15 is effective for the Company beginning in the first quarter of fiscal 2019. Early adoption is permitted, provided that all of the amendments are adopted in the same period. The guidance requires application using a retrospective transition method. The Company adopted ASU 2016-15 in the first quarter of fiscal 2018 and it did not have an impact on its Consolidated Financial Statements.

In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (ASU 2016-16), which is intended to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. This update removes the current exception in GAAP prohibiting entities from recognizing current and deferred income tax expenses or benefits related to transfer of assets, other than inventory, within the consolidated entity. The current exception to defer the recognition of any tax impact on the transfer of inventory within the consolidated entity until it is sold to a third party remains unaffected. ASU 2016-16 is effective for the Company beginning in the first quarter of fiscal 2019 and early adoption is permitted. The Company adopted ASU 2016-16 in the first quarter of fiscal 2018 and it did not have an impact on its Consolidated Financial Statements.

In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718) (ASU 2017-09). The amendments in ASU 2017-09 provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. ASU 2017-09 is effective for the Company beginning in the first quarter of fiscal 2019 and early adoption is permitted. The Company adopted ASU 2017-09 in the first quarter of fiscal 2018 and it did not have an impact on its Consolidated Financial Statements.

New Accounting Standards Not Yet Adopted In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09), 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 is effective for the Company beginning in the first quarter of fiscal 2019. The amendments in this update are to be applied on a retrospective basis, either to each prior reporting period presented (full retrospective method) or by presenting the cumulative effect of applying the update recognized at the date of initial application (modified retrospective method). The Company is evaluating the impact of the adoption of the standard on its Consolidated Financial Statements. A project team has been established, has conducted surveys of the businesses, is performing revenue contract analyses to gather information and identify where potential differences could result in applying the requirements of the new standard and has begun assessing the financial impact of the new standard on its Consolidated Financial Statements. The results of this assessment have not yet been determined. During the quarter ended April 30, 2018, the Company made the decision that it anticipates adopting the standard using the modified retrospective method, applying the guidance to those contracts which were not completed as of August 1, 2018.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (ASU 2016-02), which amends the guidance requiring companies to recognize assets and liabilities for leases with lease terms of more than twelve months. The new guidance will require companies to record both capital and operating leases on the balance sheet. This accounting guidance is effective for the Company beginning in the first quarter of fiscal 2020 on a modified retrospective basis, and early adoption is permitted. The Company is evaluating the impact of the adoption of ASU 2016-02 on its Consolidated Financial Statements.

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 is effective for the Company beginning in the first quarter of fiscal 2019. The Company does not expect the application of ASU 2017-01 will 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 is effective for the Company beginning in the first quarter of fiscal 2019. The Company is evaluating the impact of the adoption of ASU 2017-07 on its Consolidated Statements of Earnings.

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, as well as 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 is evaluating the impact of the adoption of ASU 2017-12 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 time of 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. ASU 2018-02 is effective for the Company beginning in the first quarter of fiscal 2020, and early adoption is permitted.