Nature of Operations and Accounting Policies (Policies)	9 Months Ended
Apr. 30, 2018
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Thor Industries, Inc. was founded in 1980 and, through its subsidiaries (collectively, the “Company”), manufactures a wide range of recreational vehicles (“RVs”) at various manufacturing facilities located primarily in Indiana, with additional facilities in Ohio, Oregon, Idaho and Michigan. These products are sold to independent, non-franchise dealers primarily throughout the United States and Canada. Unless the context requires or indicates otherwise, all references to “Thor”, the “Company”, “we”, “our” and “us” refer to Thor Industries, Inc. and its subsidiaries. The July 31, 2017 amounts are derived from the annual audited financial statements. The interim financial statements are unaudited. In the opinion of management, all adjustments (which consist of normal recurring adjustments) necessary to present fairly the financial position, results of operations and cash flows for the interim periods presented have been made. These financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the fiscal year ended July 31, 2017. Due to seasonality within the recreational vehicle industry, among other factors, annualizing the results of operations for the nine months ended April 30, 2018 would not necessarily be indicative of the results expected for a full fiscal year.
Accounting Pronouncements	Accounting Pronouncements In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2017-04, “Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” which eliminates the requirement to calculate the implied fair value of goodwill to measure a goodwill impairment charge (referred to as Step 2 in the goodwill impairment test). Instead, if the carrying amount of a reporting unit exceeds its fair value, an impairment charge equal to that excess shall be recognized, not to exceed the amount of goodwill allocated to the reporting unit. This ASU is effective for annual and any interim impairment tests for periods beginning after December 15, 2019, with early adoption permitted after January 1, 2017. This ASU is effective for the Company in its fiscal year 2021 beginning on August 1, 2020. The Company is currently evaluating the impact of this ASU on its consolidated financial statements, which will depend on the outcomes of future goodwill impairment tests. In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842),” which provides guidance on the recognition, measurement, presentation, and disclosure of leases. ASU No. 2016-02 requires the recognition of lease assets and lease liabilities by lessees for all leases with terms greater than 12 months. The principal difference from current guidance is that the lease assets and lease liabilities arising from operating leases will be recognized on the Consolidated Balance Sheet. This ASU is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. Early adoption is permitted. This ASU is effective for the Company in its fiscal year 2020 beginning on August 1, 2019. The Company is currently evaluating the impact that implementing this ASU will have on its financial statements. In July 2015, the FASB issued ASU No. 2015-11, “Inventory (Topic 330): Simplifying the Measurement of Inventory.” ASU No. 2015-11 requires inventory measured using any method other than last-in, first-out (“LIFO”) or the retail inventory method to be subsequently measured at the lower of cost or net realizable value, rather than at the lower of cost or market. Net realizable value is defined as the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. Under this ASU, subsequent measurement of inventory using the LIFO and retail inventory method is unchanged. ASU No. 2015-11 is effective prospectively for fiscal years, and for interim periods within those years, beginning after December 15, 2016. The Company adopted ASU No. 2015-11 on August 1, 2017 and there was no material impact on the Condensed Consolidated Financial Statements. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. This ASU will supersede most current revenue recognition guidance. Under this ASU, entities are required to identify the contract with a customer, identify the separate performance obligations in the contract, determine the transaction price, allocate the transaction price to the separate performance obligations in the contract and recognize the appropriate amount of revenue when (or as) the entity satisfies each performance obligation. This ASU will also require additional qualitative and quantitative disclosures about contracts with customers, significant judgments made in applying the revenue guidance, and assets recognized from the costs to obtain or fulfill a contract. ASU No. 2014-09 is effective for fiscal years, and the interim periods within those years, beginning after December 15, 2017. This ASU is effective for the Company in its fiscal year 2019 beginning on August 1, 2018. In applying this ASU, entities have the option of using either a full retrospective transition or a modified retrospective approach with the cumulative effect recognized as of the date of adoption. The Company plans to use the modified retrospective approach in applying this ASU. The Company is in the process of analyzing and quantifying the adoption impact of this ASU as well as evaluating the impact to internal controls, business processes and financial statement disclosures under this ASU. While the Company is still completing its assessment of all the potential impacts of this ASU, the Company does not anticipate adoption will have a material impact to the consolidated financial statements. The ASU will, however, require more extensive revenue-related disclosures. The Company will continue evaluation of the adoption of this ASU through the date of adoption, including assessing the impact of required financial statement disclosures.

Accounting Pronouncements

In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2017-04, “Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” which eliminates the requirement to calculate the implied fair value of goodwill to measure a goodwill impairment charge (referred to as Step 2 in the goodwill impairment test). Instead, if the carrying amount of a reporting unit exceeds its fair value, an impairment charge equal to that excess shall be recognized, not to exceed the amount of goodwill allocated to the reporting unit. This ASU is effective for annual and any interim impairment tests for periods beginning after December 15, 2019, with early adoption permitted after January 1, 2017. This ASU is effective for the Company in its fiscal year 2021 beginning on August 1, 2020. The Company is currently evaluating the impact of this ASU on its consolidated financial statements, which will depend on the outcomes of future goodwill impairment tests.

In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842),” which provides guidance on the recognition, measurement, presentation, and disclosure of leases. ASU No. 2016-02 requires the recognition of lease assets and lease liabilities by lessees for all leases with terms greater than 12 months. The principal difference from current guidance is that the lease assets and lease liabilities arising from operating leases will be recognized on the Consolidated Balance Sheet. This ASU is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. Early adoption is permitted. This ASU is effective for the Company in its fiscal year 2020 beginning on August 1, 2019. The Company is currently evaluating the impact that implementing this ASU will have on its financial statements.

In July 2015, the FASB issued ASU No. 2015-11, “Inventory (Topic 330): Simplifying the Measurement of Inventory.” ASU No. 2015-11 requires inventory measured using any method other than last-in, first-out (“LIFO”) or the retail inventory method to be subsequently measured at the lower of cost or net realizable value, rather than at the lower of cost or market. Net realizable value is defined as the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. Under this ASU, subsequent measurement of inventory using the LIFO and retail inventory method is unchanged. ASU No. 2015-11 is effective prospectively for fiscal years, and for interim periods within those years, beginning after December 15, 2016. The Company adopted ASU No. 2015-11 on August 1, 2017 and there was no material impact on the Condensed Consolidated Financial Statements.

In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. This ASU will supersede most current revenue recognition guidance. Under this ASU, entities are required to identify the contract with a customer, identify the separate performance obligations in the contract, determine the transaction price, allocate the transaction price to the separate performance obligations in the contract and recognize the appropriate amount of revenue when (or as) the entity satisfies each performance obligation. This ASU will also require additional qualitative and quantitative disclosures about contracts with customers, significant judgments made in applying the revenue guidance, and assets recognized from the costs to obtain or fulfill a contract. ASU No. 2014-09 is effective for fiscal years, and the interim periods within those years, beginning after December 15, 2017. This ASU is effective for the Company in its fiscal year 2019 beginning on August 1, 2018. In applying this ASU, entities have the option of using either a full retrospective transition or a modified retrospective approach with the cumulative effect recognized as of the date of adoption. The Company plans to use the modified retrospective approach in applying this ASU.

The Company is in the process of analyzing and quantifying the adoption impact of this ASU as well as evaluating the impact to internal controls, business processes and financial statement disclosures under this ASU. While the Company is still completing its assessment of all the potential impacts of this ASU, the Company does not anticipate adoption will have a material impact to the consolidated financial statements. The ASU will, however, require more extensive revenue-related disclosures. The Company will continue evaluation of the adoption of this ASU through the date of adoption, including assessing the impact of required financial statement disclosures.