Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Oct. 31, 2013	Jul. 31, 2013
Fair Value Disclosures Textual [Abstract]
Fair value of investments in hedge funds	$ 9.0	$ 8.3
Carrying value of investments	1.5	1.5
Long-term Investments [Member]
Fair Value Disclosures Textual [Abstract]
Fair value of investments in hedge funds	8.9	8.2
Other Current Assets [Member]
Fair Value Disclosures Textual [Abstract]
Fair value of investments in hedge funds	$ 0.1	$ 0.1

This item represents a financial instrument (as defined) for which it is not practicable to estimate fair value. Such disclosure may be for an individual financial instrument or a class of financial instruments.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 325

-SubTopic 20

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=29638263&loc=d3e39828-111592

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