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Summary of Significant Accounting Policies - Self-Insurance Liabilities and Related Costs - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Summary Of Significant Accounting Policies [Line Items]
Maximum exposure workers' compensation plan per individual event	$ 1,000
Self insurance reserves	10,280	11,362
Automobile Plan [Member]
Summary Of Significant Accounting Policies [Line Items]
Maximum exposure workers' compensation plan per individual event	$ 1,000

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- Definition

Maximum exposure per individual event.

+ References

No definition available.

+ Details

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- Definition

Carrying amount (including both current and noncurrent portions) of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, typically arising from workmen's compensation-type of incidents and personal injury to nonemployees from accidents on the entity's property.

+ References

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 210.5-02.24)

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

+ Details

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