Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
Apr. 30, 2016 USD ($) people state segment merchandise_category store	Apr. 30, 2015 USD ($)	Apr. 30, 2014 USD ($)
Accounting Policies [Abstract]
Number of stores \| store	1,931
Number of states in which entity operates \| state	14
Population of communities (many less than) \| people	5,000
Concentration Risk
Excess of current cost over the stated LIFO Value	$ 58,432	$ 53,428
Goodwill	128,566	127,046
Asset impairment charges	1,625	1,785	$ 2,542
Recorded asset retirement obligation (net of amortization)	9,788	9,234
Discounted liability of asset retirement obligation	14,975	14,014
Self-insurance reserves	$ 35,535	31,389
Number of operating segments \| segment	1
Number of reportable segments \| segment	1
Number of merchandise categories \| merchandise_category	3
Fuel
Concentration Risk
Excise taxes collected	$ 818,000	$ 715,000	$ 646,000
Fuel \| Retail Sales
Concentration Risk
Concentration risk percentage	59.00%
Grocery & other merchandise \| Retail Sales
Concentration Risk
Concentration risk percentage	29.00%
Prepared food & fountain \| Retail Sales
Concentration Risk
Concentration risk percentage	12.00%

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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The excise taxes collected by a public utility and reported in revenues if the amount of excise taxes is equal to 1 percent or more of such total.

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