Additional Information for Certain Balance Sheet Accounts (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013		Jul. 31, 2012
Accounts receivable, net of allowance:
Billed	$ 82,704		$ 91,143
Unbilled	3,472	[1]	4,974	[1]
Accounts receivable, net of allowance for doubtful accounts of $482 and $344 as of January 31, 2013 and July 31, 2012, respectively	86,176		96,117
Inventory:
Raw materials	87,126		73,657
Work-in-process	9,718		9,994
Finished goods	28,822		25,293
Inventory	125,666		108,944
Accrued liabilities:
Accrued employee compensation and benefits	17,049		25,153
Accrued restructuring charges			277
Accrued warranty	5,457		5,634
Other	8,303		10,682
Accrued liabilities	30,809		41,746
Advance payments and deferred revenue:
Deferred revenue	11,277	[2]	11,551	[2]
Customer deposits	2,597		2,772
Advance payments and deferred revenue	$ 13,874		$ 14,323

[1] Total unbilled receivables at January 31, 2013 and July 31, 2012 were $6,958 and $7,652, respectively. At January 31, 2013 and July 31, 2012, the long-term portion of unbilled receivables of $3,486 and $2,679, respectively, was included in non-current other assets.

[2] Total deferred revenue at January 31, 2013 and July 31, 2012 was $11,789 and $12,267, respectively. At January 31, 2013 and July 31, 2012, the long-term portion of deferred revenue of $512 and $716, respectively, was included in non-current other liabilities.