Present value of the estimated aggregate accrual for damages arising from third-party use of the entity's product(s) or process(es) as of the balance sheet date (if the accrual qualifies for discounting).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 5.Y.Q1)

-URI http://asc.fasb.org/extlink&oid=6572457&loc=d3e149879-122751

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section Y

-Paragraph Question 1

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

Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jan. 31, 2013	Jul. 31, 2012
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Third-party claims for damages from company's product
Operating lease expiration year	2021
Purchase Commitment
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Non-cancelable inventory commitments	15.3	15.1
Employee and Board of Director Member
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Claims for damages in connection with services