Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Jan. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying condensed consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (GAAP) have been condensed or omitted pursuant to such rules and regulations.
New Accounting Pronouncements	In April 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2015-03, "Interest-Imputation of Interest (Subtopic 835-30)", which provided guidance on the presentation of debt issuance costs. The new standard requires that debt issuance costs be recorded as a reduction from the face amount of the related debt, with amortization recorded as interest expense, rather than recording as a deferred asset. The Company adopted this standard in the quarter ended July 31, 2016, retrospectively to all prior periods. The adoption of this standard did not have a material impact on the financial statements. Also, in March 2016, the FASB issued ASU 2016-09, "Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting". The goal of this update is to simplify 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. This update was effective for the Company beginning May 1, 2017 with early adoption permitted. The Company chose to early adopt this standard in the quarter ended July 31, 2016. See Footnote 5 for further discussion of the impact of adoption.
Revenue Recognition	The Company recognizes retail sales of fuel, grocery and other merchandise, prepared food and fountain and other revenue at the time of the sale to the customer. Renewable Identification Numbers (RINs) are treated as a reduction in cost of goods sold in the period the Company commits to a price and agrees to sell the RIN. Vendor rebates in the form of rack display allowances are treated as a reduction in cost of goods sold and are recognized pro rata over the period covered by the applicable rebate agreement. Vendor rebates in the form of billbacks are treated as a reduction in cost of goods sold and are recognized at the time the product is sold.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.