Significant Accounting Policies (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010
Significant Accounting Policies [Line Items]
Number of stores	1,699
Number of states in which entity operates	11
Population of communities stores are located within	5,000
Excess of current cost over the stated LIFO value	$ 41,805	$ 36,698
Goodwill	104,385	88,042
Asset impaiment charge	226	348	100
Excise taxes colleted from customers on retail gasoline sales	527,000	495,000	454,000
Asset retirement obligation in other assets net of amortization	7,343	6,926
Asset retirement obligation discounted liability recorded in other long-term liabilities	$ 11,313	$ 10,549
Gasoline [Member]
Significant Accounting Policies [Line Items]
Percentage of sales	73.00%
Grocery And Other Merchandise [Member]
Significant Accounting Policies [Line Items]
Percentage of sales	20.00%
Prepared Food & Fountain [Member]
Significant Accounting Policies [Line Items]
Percentage of sales	7.00%

Asset Retirement Obligation In Other Assets Net Of Amortization.

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- Definition

Population Of Communities

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- Definition

The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value.

+ References

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- Definition

Amount of asset retirement obligations incurred during the period.

+ References

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- Definition

The excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized.

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- Definition

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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Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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- Definition

The number of states the entity operates in as of the balance sheet date.

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Represents the number of stores.

+ References

No definition available.

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- Definition

The percentage of net product revenue to total net revenue from the sale of goods as of year end.

+ References

No definition available.

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