Additional Information for Certain Balance Sheet Accounts (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013		Jul. 31, 2012
Accounts receivable, net of allowance:
Billed	$ 82,942		$ 91,143
Unbilled	3,888	[1]	4,974	[1]
Accounts receivable, net of allowance for doubtful accounts of $2,709 and $344 as of April 30, 2013 and July 31, 2012, respectively	86,830		96,117
Inventory:
Raw materials	95,041		73,657
Work-in-process	10,134		9,994
Finished goods	35,889		25,293
Inventory	141,064		108,944
Accrued liabilities:
Accrued employee compensation and benefits	20,414		25,153
Accrued restructuring charges	465		277
Accrued warranty	6,455		5,634
Other	10,042		10,682
Accrued liabilities	37,376		41,746
Advance payments and deferred revenue:
Deferred revenue	10,270	[2]	11,551	[2]
Customer deposits	3,283		2,772
Advance payments and deferred revenue	$ 13,553		$ 14,323

[1] Total unbilled receivables at April 30, 2013 and July 31, 2012 were $6,331 and $7,652, respectively. At April 30, 2013 and July 31, 2012, the long-term portion of unbilled receivables of $2,443 and $2,678, respectively, was included in non-current other assets.

[2] Total deferred revenue at April 30, 2013 and July 31, 2012 was $11,636 and $12,267, respectively. At April 30, 2013 and July 31, 2012, the long-term portion of deferred revenue of $1,366 and $716, respectively, was included in non-current other liabilities.