Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Jul. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of Cantel and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Certain prior year amounts have been reclassified to conform to the current year's presentation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires us to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. On an ongoing basis, we evaluate the adequacy of our reserves and the estimates used in calculations of reserves as well as other judgmental financial statement items, including, but not limited to: collectability of accounts receivable, volume rebates and trade-in allowances, inventory values and obsolescence reserves, warranty reserves, contingent consideration, contingent guaranteed obligations, depreciation and amortization periods, deferred income taxes, goodwill and intangible assets, impairment of long-lived assets, unrecognized tax benefits for uncertain tax positions, reserves for legal exposure, stock-based compensation and expense accruals. Such estimates and assumptions are subjective in nature. We reflect such amounts based upon the most recent information available.
Subsequent Events	Subsequent Events We performed a review of events subsequent to July 31, 2018 through the date of issuance of the accompanying consolidated financial statements.
Revenue Recognition	Revenue Recognition Revenue on product sales is recognized as products are shipped to customers and title passes. The passing of title is determined based upon the FOB terms specified for each shipment. With respect to endoscopy and dialysis products, shipment terms are generally FOB origin for common carrier and when our distribution fleet is utilized (except for one large customer in dialysis and several endoscopy customers whereby all products are shipped FOB destination and include risk of loss provisions). With respect to water purification and filtration and healthcare disposable products, shipment terms may be either FOB origin or destination. Customer acceptance for the majority of our product sales occurs at the time of delivery. With respect to a portion of water purification and filtration and endoscopy product sales, equipment is sold as part of a system for which the equipment is functionally interdependent or the customer’s purchase order specifies “ship-complete” as a condition of delivery. Revenue recognition on such sales is deferred until all equipment has been delivered, or post-delivery obligations such as installation have been substantially fulfilled such that the products are deemed functional by the end-user. All shipping and handling fees invoiced to customers, such as freight, are recorded as revenue (and related costs are included within cost of sales) at the time the sale is recognized. A portion of our endoscopy, water purification and filtration and dialysis sales are recognized as multiple element arrangements, whereby revenue is allocated to the equipment, installation and consumable components based upon vendor specific objective evidence, which includes comparable historical transactions of similar equipment, installation and consumables sold as stand-alone components. If vendor-specific objective evidence of selling price is not available, we allocate revenue to the elements of the bundled arrangement using the estimated selling price method in order to qualify the components as separate units of accounting. Revenue on the equipment and consumables components are recognized as the equipment or consumable is shipped to customers and title passes. Revenue on the installation component is recognized when the installation is complete. Revenue on service sales is recognized when repairs are completed at the customer’s location or when repairs are completed at our facilities and the products are shipped to customers. With respect to certain endoscopy and water purification and filtration service contracts, service revenue is recognized on a straight-line basis over the contractual term of the arrangement. Our endoscopy products and services are sold directly to hospitals and other end-users in the United States and primarily to distributors internationally except for certain countries where we sell directly to hospitals and other end-users. Water purification and filtration products and services are sold directly to hospitals, dialysis clinics, pharmaceutical and biotechnology companies, laboratories, medical products and service companies and other end-users as well as through third-party distributors. The majority of our healthcare disposable products are sold to third party distributors, and with respect to some of our sterility assurance products, to hospitals, surgery centers, physician and dental offices, dental schools, medical research companies, laboratories and other end-users. The majority of our dialysis products are sold to dialysis clinics and hospitals. Sales to all of these customers follow our revenue recognition policies. None of our sales contain right-of-return provisions. Customer claims for credit or return due to damage, defect, shortage or other reason must be pre-approved by us before credit is issued or such product is accepted for return. No cash discounts for early payment are offered except with respect to a small portion of our product sales in each segment. We do not offer price protection, although advance pricing contracts or required notice periods prior to implementation of price increases exist for certain customers with respect to many of our products. With respect to certain of our dialysis, healthcare disposables, water purification and filtration and endoscopy customers, rebates are provided. Such rebates, which consist primarily of volume rebates, are provided for as a reduction of sales at the time of revenue recognition and amounted to $8,401, $6,291, and $5,944 in fiscal 2018, 2017, and 2016, respectively. Such allowances are determined based on estimated projections of sales volume for the entire rebate periods. If it becomes known that sales volume to customers will deviate from original projections, the rebate provisions originally established would be adjusted accordingly.
Translation of Foreign Currency Financial Statements	Translation of Foreign Currency Financial Statements Assets and liabilities of our foreign subsidiaries are translated into U.S. dollars at year-end exchange rates; sales and expenses are translated using average exchange rates during the year. The cumulative effect of the translation of the accounts of the foreign subsidiaries is presented as a component of accumulated other comprehensive income or loss. Foreign exchange gains and losses related to the purchase of inventories denominated in foreign currencies are included in cost of sales and foreign exchange gains and losses related to the incurrence of operating costs denominated in foreign currencies and the conversion of foreign assets and liabilities into functional currencies are included in general and administrative expenses.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments with maturities of three months or less when purchased to be cash equivalents.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable consist of amounts due to us from normal business activities. Allowances for doubtful accounts are reserves for the estimated loss from the inability of customers to make required payments. We use historical experience as well as current market information in determining the estimate. While actual losses have historically been within management’s expectations and provisions established, if the financial condition of our customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances may be required. Alternatively, if certain customers paid their delinquent receivables, reductions in allowances may be required.
Inventories	Inventories Inventories consist of raw materials, work-in-process and finished products which are sold in the ordinary course of our business and are stated at the lower of cost (first-in, first-out) or net realizable value. In assessing the value of inventories, we must make estimates and judgments regarding reserves required for product obsolescence, aging of inventories and other issues potentially affecting the saleable condition of products. In performing such evaluations, we use historical experience as well as current market information. With few exceptions, the saleable value of our inventories has historically been within management’s expectation and provisions established, however, rapid changes in the market due to competition, technology and various other factors could impact the value of our inventories, resulting in the need for additional reserves.
Property and Equipment	Property and Equipment Property and equipment are stated at cost. Additions and improvements are capitalized, while maintenance and repair costs are expensed. When assets are retired or otherwise disposed, the cost and related accumulated depreciation or amortization is removed from the respective accounts and any resulting gain or loss is included in income. Depreciation and amortization is provided on the straight-line method over the estimated useful lives of the assets which generally range from 2-15 years for furniture and equipment, 5-40 years for buildings and improvements and the shorter of the life of the asset or the life of the lease for leasehold improvements.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Certain of our identifiable intangible assets, including customer relationships, technology, brand names, non-compete agreements and patents, are amortized using the straight-line method over their estimated useful lives which range from 3 to 20 years. Additionally, we have recorded goodwill and trademarks and trade names, all of which have indefinite useful lives and are therefore not amortized. All of our intangible assets and goodwill are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, and goodwill and intangible assets with indefinite lives are reviewed for impairment at least annually. Our management is responsible for determining if impairment exists and considers a number of factors, including third-party valuations, when making these determinations. We first assess qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than the carrying amount before proceeding to step one of the two-step quantitative goodwill impairment test, if necessary. Such qualitative factors that are assessed include evaluating a segment’s financial performance, industry and market conditions, macroeconomic conditions and specific issues that can directly affect the segment such as changes in business strategies, competition, supplier relationships, operating costs, regulatory matters, litigation and the composition of the segment’s assets due to acquisitions or other events. At May 1, 2018, because we determined through qualitative factors that the fair values of our Endoscopy, Water Purification and Filtration and Healthcare Disposables segments were unlikely to be less than the carrying value, we did not proceed to step one of the two-step quantitative goodwill impairment test for those three segments. We performed step one of the two-step quantitative goodwill impairment test for Dialysis due to the continuing shift by our customers from reusable to single-use dialyzers, which is having an adverse impact on our business and is expected to continue. In performing a detailed quantitative review for goodwill impairment, management uses a two-step process that begins with an estimation of the fair value of the related reporting units by using weighted fair value results of the discounted cash flow methodology, as well as the market multiple and comparable transaction methodologies, where applicable. The first step is a review for potential impairment, and the second step measures the amount of impairment, if any. Historically, goodwill and indefinite lived intangible assets were tested annually for impairment as of July 31 of each fiscal year. In fiscal 2018, we changed our measurement date to May 1 of each year to better align the annual impairment test with the timing of our annual strategic planning process. We perform our annual impairment review for indefinite lived intangibles by first assessing qualitative factors, such as those described above, to determine whether it is more likely than not that the fair value of such assets is less than the carrying values, and if necessary, we perform a quantitative analysis comparing the current fair value of our indefinite lived intangibles assets to their carrying values. At May 1, 2018, because we determined through qualitative factors that the fair values of all of our indefinite lived intangible assets were unlikely to be less than the carrying value, we did not perform a quantitative analysis for those assets. With respect to amortizable intangible assets when impairment indicators are present, management would determine whether expected future non-discounted cash flows would be sufficient to recover the carrying value of the assets; if not, the carrying value of the assets would be adjusted to their fair value. We did not recognize any impairment charges for goodwill or indefinite lived intangibles in the years presented.
Long-Lived Assets	Long-Lived Assets We evaluate the carrying value of long-lived assets including property, equipment and other assets whenever events or changes in circumstances indicate that the carrying value may not be recoverable. An assessment is made to determine if the sum of the expected future non-discounted cash flows from the use of the assets and eventual disposition is less than the carrying value. If the sum of the expected non-discounted cash flows is less than the carrying value, an impairment loss is recognized based on fair value. Our historical assessments of our long-lived assets have not differed significantly from the actual amounts realized. However, the determination of fair value requires us to make certain assumptions and estimates and is highly subjective. On July 31, 2018, management concluded that no other events or changes in circumstances have occurred that would indicate that the carrying amount of our long-lived assets may not be recoverable.
Other Assets	Debt Issuance Costs Debt issuance costs are capitalized and amortized to interest expense over the term of the related credit agreements.
Warranties	Warranties We provide for estimated costs that may be incurred to remedy deficiencies of quality or performance of our products at the time of revenue recognition. Most of our products have a one year warranty, although certain endoscopy and water purification and filtration products that require installation may carry a warranty period of up to 24 months. Additionally, many of our consumables, accessories, parts and service have a 90-day warranty. We record provisions for product warranties as a component of cost of sales based upon an estimate of the amounts necessary to settle existing and future claims on products sold.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense is recognized for any option or stock award grant based upon the fair value of the award. Our stock options and time-based stock awards are subject to graded vesting in which portions of the award vest ratably over the vesting period. We recognize compensation expense for the awards with performance conditions using the accelerated attribution method over the requisite service period for each separately vesting portion of the award when it is probable that the performance condition will be achieved. We record expense for the awards with market conditions ratably over the vesting period regardless of whether the market condition is satisfied. We account for forfeitures as they occur, rather than estimate forfeitures over the course of the vesting period. We determine the fair value of each time-based stock award and performance-based stock award by using the closing market price of our common stock on the last trading date immediately prior to the date of grant. We determine the fair value of each award with market conditions using a Monte Carlo simulation model on the date of grant. We estimate the fair value of each option grant on the date of grant using the Black Scholes option valuation model. The determination of fair value using valuation models is affected by our stock price as well as assumptions regarding a number of subjective variables.
Advertising Costs	Advertising Costs Our policy is to expense advertising costs as they are incurred.
Income Taxes	Income Taxes Our provision for income taxes is based on our current period income, changes in deferred income tax assets and liabilities, statutory income tax rates, changes in uncertain tax benefits and the deductibility of expenses or availability of tax credits in various taxing jurisdictions. Tax laws are complex, subject to different interpretations by the taxpayer and the respective governmental taxing authorities and are subject to future modification, expiration or repeal by government legislative bodies. We use significant judgment on a quarterly basis in determining our annual effective income tax rate and evaluating our tax positions. We regularly review our deferred tax assets for recoverability and establish a valuation allowance, if necessary, based on historical taxable income, projected future taxable income, and the expected timing of the reversals of existing temporary differences. Although realization is not assured, management believes it is more likely than not that the recorded deferred tax assets, as adjusted for valuation allowances, will be realized. Additionally, deferred tax liabilities are regularly reviewed to confirm that such amounts are appropriately stated. A review of our deferred tax items considers known future changes in various income tax rates, principally in the United States. If income tax rates were to change in the future, particularly in the United States and to a lesser extent Germany, the U.K. and Italy, our items of deferred tax could be materially affected. All of such evaluations require significant management judgments. We record liabilities for an unrecognized tax benefit when a tax benefit for an uncertain tax position is taken or expected to be taken on a tax return, but is not recognized in our consolidated financial statements because it does not meet the more-likely-than-not recognition threshold that the uncertain tax position would be sustained upon examination by the applicable taxing authority. Any adjustments upon resolution of income tax uncertainties are recognized in our results of operations. Unrecognized tax benefits are analyzed periodically and adjustments are made as events occur to warrant adjustment to the related liability. Historically, we have not had significant unrecognized tax benefits.
Recently Issued Accounting Standards	Newly Adopted Accounting Standards In September 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2015-16, “(Topic 805) Simplifying the Accounting for Measurement-Period Adjustments,” (“ASU 2015-16”). The new guidance requires an acquirer in a business combination to recognize a measurement-period adjustment during the period in which it determines the amount, and eliminates the requirement for an acquirer to account for measurement-period adjustments retrospectively. The acquirer must also disclose the amounts and reasons for adjustments to the provisional amounts. ASU 2015-16 is effective for fiscal years beginning after December 15, 2016 (our fiscal year 2018), including interim periods within that reporting period. Accordingly, we adopted ASU 2015-06 on August 1, 2017. The adoption of ASU 2015-16 did not have a material impact on our financial position, results of operations or cash flows. In July 2015, the FASB issued ASU 2015-11, “(Topic 330) Simplifying the Measurement of Inventory,” (“ASU 2015-11”). The new guidance requires companies using the first-in, first-out and average costs methods to measure inventory using the lower of cost and net realizable value, where net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. ASU 2015-11 is effective for fiscal years beginning after December 15, 2016 (our fiscal year 2018), including interim periods within that reporting period. Accordingly, we adopted ASU 2015-11 on August 1, 2017. The adoption of ASU 2015-11 did not have a material impact on our financial position, results of operations and cash flows. In January 2017, the FASB issued ASU 2017-01, “(Topic 805) Clarifying the Definition of a Business,” (“ASU 2017-01”) to clarify the definition of a business. The revised guidance creates a more robust framework to use in determining whether a set of assets and activities is a business. The guidance will be applied on a prospective basis on or after the effective date. ASU 2017-01 is effective for fiscal years beginning after December 15, 2017 (our fiscal year 2019), including interim periods within that reporting period. We early adopted ASU-2017-01 on August 1, 2017. The adoption of ASU 2017-01 did not have a material impact on our financial position, results of operations or cash flows. Recently Issued Accounting Standards In February 2018, the FASB issued ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” (“ASU 2018-02”) to allow for the reclassification from accumulated other comprehensive income to retained earnings of stranded tax effects resulting from the Tax Cuts and Jobs Act enacted in December 2017. ASU 2018-02 is effective for fiscal years beginning after December 15, 2018 (our fiscal year 2020), including interim periods within that reporting period. The adoption of ASU 2018-02 is not expected to have a significant impact on our financial position, results of operations or cash flows. In August 2017, the FASB issued ASU 2017-12, “Targeted Improvements to Accounting for Hedging Activities” (“ASU 2017-12”) to improve the financial reporting of hedging relationships to better portray the economic results of an entity's risk management activities in its financial statements. ASU 2017-12 is effective for fiscal years beginning after December 15, 2018 (our fiscal year 2020), including interim periods within that reporting period. The adoption of ASU 2017-12 is not expected to have a significant impact on our financial position, results of operations or cash flows. In May 2017, the FASB issued ASU 2017-09, “(Topic 718) Scope of Modification Accounting,” ("ASU 2017-09") to 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 2017-12 is effective for fiscal years beginning after December 15, 2017 (our fiscal year 2019), including interim periods within that reporting period. The adoption of ASU 2017-09 is not expected to have a significant impact on our financial position, results of operations or cash flows. In January 2017, the FASB issued ASU 2017-04, “(Topic 350) Simplifying the Test for Goodwill Impairment,” (“ASU 2017-04”) to simplify the test for goodwill impairment. The revised guidance eliminates the existing Step 2 of the goodwill impairment test which required an entity to compute the implied fair value of its goodwill at the testing date in order to measure the amount of the impairment charge when the fair value of the reporting unit failed Step 1 of the goodwill impairment test. Under the revised guidance, an entity would recognize an impairment charge for the amount by which the carrying amount of the reporting unit exceeds its fair value; however, the loss recognized would not exceed the total amount of goodwill allocated to the reporting unit. The guidance will be applied on a prospective basis on or after the effective date. ASU 2017-04 is effective for fiscal years beginning after December 31, 2019 (our fiscal year 2021) and early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of ASU 2017-04 is not expected to have a significant impact on our financial position, results of operations or cash flows. In August 2016, the FASB issued ASU 2016-15, “(Topic 230) Classification of Certain Cash Receipts and Cash Payments,” (“ASU 2016-15”). This new guidance will make eight targeted changes to how cash receipts and cash payments are presented and classified in the statement of cash flows. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017 (our fiscal year 2019). ASU 2016-15 will require adoption on a retrospective basis unless it is impracticable to apply, in which case we would be required to apply the amendments prospectively as of the earliest date practicable. The adoption of ASU 2016-15 is not expected to have a significant impact on our financial position, results of operations or cash flows. In February 2016, the FASB issued ASU 2016-02, “(Topic 842) Leases,” (“ASU 2016-02”). The new guidance requires the recording of assets and liabilities arising from leases on the balance sheet accompanied by enhanced qualitative and quantitative disclosures in the notes to the financial statements. The new guidance is expected to provide transparency of information and comparability among organizations. ASU 2016-02 is effective for fiscal years beginning after December 31, 2018 (our fiscal year 2020), including interim periods within that reporting period. Early adoption is permitted as of the beginning of an interim or annual period. We are currently in the process of evaluating the impact of ASU 2016-02 on our financial position, results of operations and cash flows. In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” (“ASU 2014-09”), which will supersede the revenue recognition requirements in Accounting Standards Codification 605, “Revenue Recognition” (“ASC 605”). ASU 2014-09 is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. It also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. In August 2015, the FASB issued ASU 2015-14, “Revenue from Contracts with Customers (Topic 606),” (“ASU 2015-14”), which defers the effective date of ASU 2014-09 by one year to fiscal years beginning after December 15, 2017 (our fiscal year 2019), including interim periods within that reporting period. In May 2016, the FASB issued ASU 2016-12, “Revenue from Contracts with Customers (Topic 606),” (“ASU 2016-12”), which provided narrow scope improvements and practical expedients relating to ASU 2014-09. In preparation for our adoption of ASU 2014-09 and ASU 2016-12 on August 1, 2018, we have obtained representative samples of contracts and other forms of agreements with our customers in the United States and international locations and have evaluated the provisions contained therein in light of the five-step model specified by the new guidance. We have also evaluated the impact of the new standard on certain common practices currently employed by us and by other health care manufacturers and service providers, such as multiple-element arrangements, deferred revenues, warranties, rebates and other pricing allowances. We have reached conclusions on our accounting assessments related to the standard and finalized updates to our accounting policies, processes and controls and will adopt the new standard on August 1, 2018 using the modified retrospective approach. We expect to record an immaterial adjustment to retained earnings upon adoption of Topic 606 in the first quarter of fiscal 2019, primarily related to the timing of revenue recognition for the shipment of products in both our Endoscopy and Water Purification and Filtration segments where risk of loss provisions are present (“synthetic FOB destination”). The new standard does not require us to defer revenue for these products and allows us to recognize revenue at the time of shipment. The adjustment to retained earnings also includes the impact of the change in timing of revenue recognition associated with software licensing arrangements in our Endoscopy segment. Overall, we expect the adoption of Topic 606 to have an immaterial impact on our fiscal 2019 financial position, results of operations or cash flows. The timing of revenue recognition for our primary revenue streams will not change. Additionally, we have completed our assessment of new disclosure requirements. Upon adoption of Topic 606, we will provide additional disclosures in the notes to the consolidated financial statements, specifically related to performance obligations and multiple-element revenue streams. We have designed new internal controls that will be implemented in the first quarter of fiscal 2019 to address risks associated with applying the five-step model. Additionally, we have established monitoring controls to identify new sales arrangements and changes in our business environment that could impact our current accounting assessment.