Additional Information for Certain Balance Sheet Accounts (Detail) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2012		Jul. 31, 2012
Accounts receivable, net of allowance:
Billed	$ 72,758		$ 91,143
Unbilled	5,524	[1]	4,974	[1]
Accounts receivable, net of allowance for doubtful accounts of $420 and $344 as of October 31, 2012 and July 31, 2012, respectively	78,282		96,117
Inventories:
Raw materials	85,982		73,657
Work-in-process	10,349		9,994
Finished goods	26,994		25,293
Inventories	123,325		108,944
Accrued liabilities:
Accrued employee compensation and benefits	16,099		25,153
Accrued restructuring charges			277
Accrued warranty	5,443		5,634
Other	7,980		10,682
Accrued liabilities	29,522		41,746
Advance payments and deferred revenue:
Deferred revenue	7,795	[2]	11,551	[2]
Customer deposits	2,788		2,772
Advance payments and deferred revenue	$ 10,583		$ 14,323

[1] Total unbilled receivables at October 31, 2012 and July 31, 2012 were $8,522 and $7,653, respectively. At October 31, 2012 and July 31, 2012, the long-term portion of unbilled receivables of $2,998 and $2,678, respectively, was included in non-current other assets.

[2] Total deferred revenue at October 31, 2012 and July 31, 2012 was $8,585 and $12,267, respectively. At October 31, 2012 and July 31, 2012, the long-term portion of deferred revenue of $790 and $716, respectively, was included in non-current other liabilities.