Summary of Significant Accounting Policies (Policies)	12 Months Ended
Apr. 28, 2018
Accounting Policies [Abstract]
Description of Business	Patterson Companies, Inc. (referred to herein as “Patterson” or in the first person notations “we,” “our,” and “us”) is a value-added specialty distributor serving the U.S. and Canadian dental supply and the U.S., Canadian and U.K. animal health supply markets. Patterson has three reportable segments: Dental, Animal Health and Corporate.
Basis of Presentation	The consolidated financial statements include the accounts of our wholly owned subsidiaries. Intercompany transactions and balances have been eliminated in consolidation. The respective assets of PDC Funding Company, LLC and PDC Funding Company II, LLC would be available first and foremost to satisfy the claims of their respective creditors. There are no known creditors of PDC Funding Company, LLC or PDC Funding Company II, LLC.
Fiscal Year End	We operate with a 52-53 week accounting convention with our fiscal year ending on the last Saturday in April. Fiscal 2018, 2017 and 2016 ended on April 28, 2018, April 29, 2017 and April 30, 2016, respectively. Fiscal 2018 and 2017 consisted of 52 weeks, while fiscal 2016 consisted of 53 weeks. Fiscal 2019 will end on April 27, 2019 and will consist of 52 weeks.
Use of Estimates in the Preparation of Financial Statements	The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Reclassifications	.
Cash and Cash Equivalents	Cash equivalents consist primarily of investments in money market funds and government securities. The maturity of these securities at the time of purchase is 90 days or less. All cash and cash equivalents are classified as available-for-sale and carried at fair value, which approximates cost.
Inventory	Inventory consists of merchandise held for sale and is stated at the lower of cost or market. The cost of our inventory includes the amount we pay to our suppliers to acquire inventory and freight costs incurred in connection with the delivery of product to our distribution centers and our other locations. Cost is determined using the last-in, first-out ("LIFO") method for all inventories, except for foreign inventories, which are valued using the first-in, first-out ("FIFO") method.
Property and Equipment	Property and equipment are stated at cost. Depreciation is calculated on the straight-line method over estimated useful lives of up to 39 years for buildings or the expected remaining life of purchased buildings, the term of the lease for leasehold improvements, 3 to 10 years for computer hardware and software, and 5 to 10 years for furniture and equipment.
Goodwill and Other Indefinite-Lived Intangible Assets	Goodwill represents the excess of cost over the fair value of identifiable net assets of businesses acquired. We have two reporting units as of April 28, 2018; Dental and Animal Health. Our Corporate reportable segment's assets and liabilities, and net sales and expenses, are allocated to the two reporting units. Other indefinite-lived intangible assets include copyrights, trade names and trademarks. We assess goodwill for impairment annually and whenever an event occurs or circumstances change that would indicate that the carrying amount may be impaired. If we determine that the fair value of the reporting unit may be less than its carrying amount, we evaluate goodwill using a two-step impairment test. Otherwise, we conclude that no impairment is indicated and we do not perform the two-step impairment test. In fiscal 2018, we determined it was appropriate to perform a two-step impairment test. The first step of the goodwill impairment test compares the book value of a reporting unit, including goodwill, with its fair value, as determined primarily by its discounted cash flows. If the book value of a reporting unit exceeds its fair value, the second step of the impairment test is performed to determine the amount of goodwill impairment loss to be recorded. The determination of fair value involves uncertainties because it requires management to make assumptions and to apply judgment to estimate industry and economic factors and the profitability of future business strategies. Patterson conducts impairment testing based on current business strategy in light of present industry and economic conditions, as well as future expectations. Additionally, in assessing goodwill for impairment, the reasonableness of the implied control premium is considered based on market capitalizations and recent market transactions. Other indefinite-lived intangible assets are assessed for impairment by comparing the carrying value of an asset with its fair value. If the carrying value exceeds fair value, an impairment loss is recognized in an amount equal to the excess. The determination of fair value involves assumptions, including projected revenues and gross profit levels, as well as consideration of any factors that may indicate potential impairment.
Long-Lived Assets	Long-lived assets, including definite-lived intangible assets, are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable through the estimated undiscounted future cash flows derived from such assets. Our definite-lived intangible assets primarily consist of customer relationships, trade names and trademarks. When impairment exists, the related assets are written down to fair value using level 3 inputs, as discussed further in Note 9.
Financial Instruments	We account for derivative financial instruments under the provisions of Accounting Standards Codification ("ASC") Topic 815, “Derivatives and Hedging.” Our use of derivative financial instruments is generally limited to managing well-defined interest rate risks. We do not use financial instruments or derivatives for any trading purposes.
Revenue Recognition	Revenues are generated from the sale of consumable products, equipment, software products and services, technical service parts and labor, freight and delivery charges, and other sources. Revenues are recognized when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed or determinable, and there is reasonable assurance of collection of the sale. Estimates for returns, damaged goods, rebates, loyalty programs and other revenue allowances are made at the time the revenue is recognized based on the historical experience for such items. In addition to revenues generated from the distribution of consumable products under conventional arrangements (buy/sell agreements) where the full market value of the product is recorded as revenue, the animal health segment may earn a small amount of commission income for services provided under agency agreements with certain pharmaceutical manufacturers. The services generally consist of detailing the product and taking the customer’s order. The agency agreement contrasts to a buy/sell agreement in that the animal health segment does not purchase and handle the product or bill and collect from the customer in an agency relationship with a vendor. Consumable product sales are recorded upon delivery, except in those circumstances where terms of the sale are FOB shipping point, in which case sales are recorded upon shipment. Commissions under agency agreements are recorded when the services are provided. Equipment and software product revenues are recognized upon delivery and, if necessary, installation. In those circumstances where terms of the sale are FOB shipping point, revenues are recognized when products are transferred to the shipping carrier. Revenue derived from post contract customer support for software is deferred and recognized ratably over the period in which the support is provided. Patterson provides financing for select equipment sales. See Note 7 for more information regarding customer financing. Other revenue, including freight and delivery charges and technical service parts and labor, is recognized when the related product revenue is recognized or when the product or services are provided to the customer. The receivables that result from the recognition of revenue are reported net of the related allowances discussed above. Patterson maintains a valuation allowance based upon the expected collectability of receivables held. Estimates are used to determine the valuation allowance and are based on several factors, including historical collection data, economic trends and credit worthiness of customers. Receivables are written off when we determine the amounts to be uncollectible, typically upon customer bankruptcy or non-response to continuous collection efforts. The portions of receivable amounts that are not expected to be collected during the next twelve months are classified as long-term. Patterson has a relatively large, dispersed customer base and no single customer accounts for more than 10% of consolidated net sales. In addition, the equipment sold to customers under finance contracts generally serves as collateral for the contract and the customer provides a personal guarantee as well. Net sales do not include sales tax as we are considered a pass-through conduit for collecting and remitting sales tax.
Patterson Advantage Loyalty Program	The Dental segment provides a point-based awards program to qualifying customers involving the issuance of “Patterson Advantage dollars” which can be used toward equipment and technology purchases. Patterson Advantage dollars earned during a program year expire one year after the end of the program year. The cost and corresponding liability associated with the program are recognized as contra-revenue in accordance with ASC Topic 605-50, “Revenue Recognition-Customer Payments and Incentives.” As of April 28, 2018, we believe we have sufficient experience with the program to reasonably estimate the amount of Patterson Advantage dollars that will not be redeemed and thus have recorded a liability for 87% of the maximum potential amount that could be redeemed. We use the redemption recognition method and we recognize the estimated value of unused Advantage dollars as a percentage of Patterson Advantage dollars earned. Breakage recognized was immaterial to all periods presented.
Freight and Delivery Charges	Freight and delivery charges are included in cost of sales in the consolidated statements of income.
Advertising	We expense all advertising and promotional costs as incurred, except for direct marketing expenses, which are expensed over the shorter of the life of the asset or one year.
Income Taxes	The liability method is used to account for income tax expense. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Valuation allowances are established for deferred tax assets if, after assessment of available positive and negative evidence, it is more likely than not that the deferred tax asset will not be fully realized.
Employee Stock Ownership Plan (ESOP)	Compensation expense related to our defined contribution ESOP is computed based on the shares allocated method.
Self-insurance	Patterson is self-insured for certain losses related to general liability, product liability, automobile, workers’ compensation and medical claims. We estimate our liabilities based upon an analysis of historical data and actuarial estimates. While current estimates are believed reasonable based on information currently available, actual results could differ and affect financial results due to changes in the amount or frequency of claims, medical cost inflation or other factors. Historically, actual results related to these types of claims have not varied significantly from estimated amounts.
Stock-based Compensation	We recognize stock-based compensation expense based on estimated grant date fair values. The grant date fair value of stock options and stock purchases made through our Employee Stock Purchase Plan and our Capital Accumulation Plan are estimated using the Black-Scholes option pricing valuation model. The grant date fair value of performance stock units that vest upon meeting certain market conditions is estimated using the Monte Carlo valuation model. These valuations require estimates to be made including expected stock price volatility which considers historical volatility trends, implied future volatility based on certain traded options and other factors. We estimate the expected life of awards based on several factors, including types of participants, vesting schedules, contractual terms and various factors surrounding exercise behavior of different groups. The grant date fair value of time-based restricted stock awards and restricted stock units is calculated based on the closing price of our common stock on the date of grant. Compensation expense for all share-based payment awards is recognized over the requisite service period (or to the date a participant becomes eligible for retirement, if earlier) for awards that are expected to vest.
Comprehensive Income	Comprehensive income is computed as net income plus certain other items that are recorded directly to stockholders’ equity. Significant items included in comprehensive income are foreign currency translation adjustments and the effective portion of cash flow hedges, net of tax. Foreign currency translation adjustments do not include a provision for income tax because earnings from foreign operations are considered to be indefinitely reinvested outside the U.S.
Earnings Per Share	The amount of basic EPS is computed by dividing net income by the weighted average number of outstanding common shares during the period. The amount of diluted EPS is computed by dividing net income by the weighted average number of outstanding common shares and common share equivalents, when dilutive, during the period.
Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Apr. 28, 2018

Patterson Companies, Inc. (referred to herein as “Patterson” or in the first person notations “we,” “our,” and “us”) is a value-added specialty distributor serving the U.S. and Canadian dental supply and the U.S., Canadian and U.K. animal health supply markets. Patterson has three reportable segments: Dental, Animal Health and Corporate.

Basis of Presentation

The consolidated financial statements include the accounts of our wholly owned subsidiaries. Intercompany transactions and balances have been eliminated in consolidation. The respective assets of PDC Funding Company, LLC and PDC Funding Company II, LLC would be available first and foremost to satisfy the claims of their respective creditors. There are no known creditors of PDC Funding Company, LLC or PDC Funding Company II, LLC.

Fiscal Year End

We operate with a 52-53 week accounting convention with our fiscal year ending on the last Saturday in April. Fiscal 2018, 2017 and 2016 ended on April 28, 2018, April 29, 2017 and April 30, 2016, respectively. Fiscal 2018 and 2017 consisted of 52 weeks, while fiscal 2016 consisted of 53 weeks. Fiscal 2019 will end on April 27, 2019 and will consist of 52 weeks.

Use of Estimates in the Preparation of Financial Statements

The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Reclassifications

Cash and Cash Equivalents

Cash equivalents consist primarily of investments in money market funds and government securities. The maturity of these securities at the time of purchase is 90 days or less. All cash and cash equivalents are classified as available-for-sale and carried at fair value, which approximates cost.

Inventory

Inventory consists of merchandise held for sale and is stated at the lower of cost or market. The cost of our inventory includes the amount we pay to our suppliers to acquire inventory and freight costs incurred in connection with the delivery of product to our distribution centers and our other locations. Cost is determined using the last-in, first-out ("LIFO") method for all inventories, except for foreign inventories, which are valued using the first-in, first-out ("FIFO") method.

Property and Equipment

Property and equipment are stated at cost. Depreciation is calculated on the straight-line method over estimated useful lives of up to 39 years for buildings or the expected remaining life of purchased buildings, the term of the lease for leasehold improvements, 3 to 10 years for computer hardware and software, and 5 to 10 years for furniture and equipment.

Goodwill and Other Indefinite-Lived Intangible Assets

Goodwill represents the excess of cost over the fair value of identifiable net assets of businesses acquired. We have two reporting units as of April 28, 2018; Dental and Animal Health. Our Corporate reportable segment's assets and liabilities, and net sales and expenses, are allocated to the two reporting units. Other indefinite-lived intangible assets include copyrights, trade names and trademarks.

We assess goodwill for impairment annually and whenever an event occurs or circumstances change that would indicate that the carrying amount may be impaired. If we determine that the fair value of the reporting unit may be less than its carrying amount, we evaluate goodwill using a two-step impairment test. Otherwise, we conclude that no impairment is indicated and we do not perform the two-step impairment test. In fiscal 2018, we determined it was appropriate to perform a two-step impairment test.

The first step of the goodwill impairment test compares the book value of a reporting unit, including goodwill, with its fair value, as determined primarily by its discounted cash flows. If the book value of a reporting unit exceeds its fair value, the second step of the impairment test is performed to determine the amount of goodwill impairment loss to be recorded. The determination of fair value involves uncertainties because it requires management to make assumptions and to apply judgment to estimate industry and economic factors and the profitability of future business strategies. Patterson conducts impairment testing based on current business strategy in light of present industry and economic conditions, as well as future expectations. Additionally, in assessing goodwill for impairment, the reasonableness of the implied control premium is considered based on market capitalizations and recent market transactions.

Other indefinite-lived intangible assets are assessed for impairment by comparing the carrying value of an asset with its fair value. If the carrying value exceeds fair value, an impairment loss is recognized in an amount equal to the excess. The determination of fair value involves assumptions, including projected revenues and gross profit levels, as well as consideration of any factors that may indicate potential impairment.

Long-Lived Assets

Long-lived assets, including definite-lived intangible assets, are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable through the estimated undiscounted future cash flows derived from such assets. Our definite-lived intangible assets primarily consist of customer relationships, trade names and trademarks. When impairment exists, the related assets are written down to fair value using level 3 inputs, as discussed further in Note 9.

Financial Instruments

We account for derivative financial instruments under the provisions of Accounting Standards Codification ("ASC") Topic 815, “Derivatives and Hedging.” Our use of derivative financial instruments is generally limited to managing well-defined interest rate risks. We do not use financial instruments or derivatives for any trading purposes.

Revenue Recognition

Revenues are generated from the sale of consumable products, equipment, software products and services, technical service parts and labor, freight and delivery charges, and other sources. Revenues are recognized when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed or determinable, and there is reasonable assurance of collection of the sale. Estimates for returns, damaged goods, rebates, loyalty programs and other revenue allowances are made at the time the revenue is recognized based on the historical experience for such items. In addition to revenues generated from the distribution of consumable products under conventional arrangements (buy/sell agreements) where the full market value of the product is recorded as revenue, the animal health segment may earn a small amount of commission income for services provided under agency agreements with certain pharmaceutical manufacturers. The services generally consist of detailing the product and taking the customer’s order. The agency agreement contrasts to a buy/sell agreement in that the animal health segment does not purchase and handle the product or bill and collect from the customer in an agency relationship with a vendor.

Consumable product sales are recorded upon delivery, except in those circumstances where terms of the sale are FOB shipping point, in which case sales are recorded upon shipment. Commissions under agency agreements are recorded when the services are provided.

Equipment and software product revenues are recognized upon delivery and, if necessary, installation. In those circumstances where terms of the sale are FOB shipping point, revenues are recognized when products are transferred to the shipping carrier. Revenue derived from post contract customer support for software is deferred and recognized ratably over the period in which the support is provided. Patterson provides financing for select equipment sales. See Note 7 for more information regarding customer financing.

Other revenue, including freight and delivery charges and technical service parts and labor, is recognized when the related product revenue is recognized or when the product or services are provided to the customer.

The receivables that result from the recognition of revenue are reported net of the related allowances discussed above. Patterson maintains a valuation allowance based upon the expected collectability of receivables held. Estimates are used to determine the valuation allowance and are based on several factors, including historical collection data, economic trends and credit worthiness of customers. Receivables are written off when we determine the amounts to be uncollectible, typically upon customer bankruptcy or non-response to continuous collection efforts. The portions of receivable amounts that are not expected to be collected during the next twelve months are classified as long-term.

Patterson has a relatively large, dispersed customer base and no single customer accounts for more than 10% of consolidated net sales. In addition, the equipment sold to customers under finance contracts generally serves as collateral for the contract and the customer provides a personal guarantee as well.

Net sales do not include sales tax as we are considered a pass-through conduit for collecting and remitting sales tax.

Patterson Advantage Loyalty Program

The Dental segment provides a point-based awards program to qualifying customers involving the issuance of “Patterson Advantage dollars” which can be used toward equipment and technology purchases. Patterson Advantage dollars earned during a program year expire one year after the end of the program year. The cost and corresponding liability associated with the program are recognized as contra-revenue in accordance with ASC Topic 605-50, “Revenue Recognition-Customer Payments and Incentives.” As of April 28, 2018, we believe we have sufficient experience with the program to reasonably estimate the amount of Patterson Advantage dollars that will not be redeemed and thus have recorded a liability for 87% of the maximum potential amount that could be redeemed. We use the redemption recognition method and we recognize the estimated value of unused Advantage dollars as a percentage of Patterson Advantage dollars earned. Breakage recognized was immaterial to all periods presented.

Freight and Delivery Charges

Freight and delivery charges are included in cost of sales in the consolidated statements of income.

Advertising

We expense all advertising and promotional costs as incurred, except for direct marketing expenses, which are expensed over the shorter of the life of the asset or one year.

Income Taxes

The liability method is used to account for income tax expense. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse.

Valuation allowances are established for deferred tax assets if, after assessment of available positive and negative evidence, it is more likely than not that the deferred tax asset will not be fully realized.

Employee Stock Ownership Plan (ESOP)

Compensation expense related to our defined contribution ESOP is computed based on the shares allocated method.

Self-insurance

Patterson is self-insured for certain losses related to general liability, product liability, automobile, workers’ compensation and medical claims. We estimate our liabilities based upon an analysis of historical data and actuarial estimates. While current estimates are believed reasonable based on information currently available, actual results could differ and affect financial results due to changes in the amount or frequency of claims, medical cost inflation or other factors. Historically, actual results related to these types of claims have not varied significantly from estimated amounts.

Stock-based Compensation

We recognize stock-based compensation expense based on estimated grant date fair values. The grant date fair value of stock options and stock purchases made through our Employee Stock Purchase Plan and our Capital Accumulation Plan are estimated using the Black-Scholes option pricing valuation model. The grant date fair value of performance stock units that vest upon meeting certain market conditions is estimated using the Monte Carlo valuation model. These valuations require estimates to be made including expected stock price volatility which considers historical volatility trends, implied future volatility based on certain traded options and other factors. We estimate the expected life of awards based on several factors, including types of participants, vesting schedules, contractual terms and various factors surrounding exercise behavior of different groups.

The grant date fair value of time-based restricted stock awards and restricted stock units is calculated based on the closing price of our common stock on the date of grant.

Compensation expense for all share-based payment awards is recognized over the requisite service period (or to the date a participant becomes eligible for retirement, if earlier) for awards that are expected to vest.

Comprehensive Income

Comprehensive income is computed as net income plus certain other items that are recorded directly to stockholders’ equity. Significant items included in comprehensive income are foreign currency translation adjustments and the effective portion of cash flow hedges, net of tax. Foreign currency translation adjustments do not include a provision for income tax because earnings from foreign operations are considered to be indefinitely reinvested outside the U.S.

Earnings Per Share

The amount of basic EPS is computed by dividing net income by the weighted average number of outstanding common shares during the period. The amount of diluted EPS is computed by dividing net income by the weighted average number of outstanding common shares and common share equivalents, when dilutive, during the period.

Recent Accounting Pronouncements