Goodwill and Intangible Assets - Components of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2013	Apr. 30, 2013
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 30,568	$ 28,703
Less accumulated amortization	(18,138)	(17,029)
Intangible assets, net	12,430	11,674
Covenants Not-to-Compete [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets	17,220	17,043
Less accumulated amortization	(15,087)	(14,800)
Intangible assets, net	2,133	2,243
Client Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets	13,348	11,660
Less accumulated amortization	(3,051)	(2,229)
Intangible assets, net	$ 10,297	$ 9,431

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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