Significant Accounting Policies (Schedule Of Inventory Values) (Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2012	Apr. 30, 2011
Significant Accounting Policies [Line Items]
Inventory	$ 170,794	$ 159,200
Gasoline [Member]
Significant Accounting Policies [Line Items]
Inventory	83,063	81,964
Merchandise [Member]
Significant Accounting Policies [Line Items]
Inventory	$ 87,731	$ 77,236

Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_InventoryGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant