Fair Value of Financial Instruments - Financial Assets and Liabilities Carried at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2013		Jul. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets, Fair Value	$ 68,471		$ 44,524
Total financial liabilities, Fair Value	4,112		4,405
Other assets, net [Member] | Marketable securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value	49,343	[1]	41,155	[1]
Prepaid expenses and other current assets [Member] | Bank Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value			1,357	[2]
Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	212	[2]	23	[2]
Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	18,744	[2]	1,414	[2]
Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Put option contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value			152	[2]
Prepaid expenses and other current assets [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	172	[2]	423	[2]
Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	3,470	[3]	3,946	[3]
Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	617	[3]	382	[3]
Accounts payable and accrued liabilities [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	25	[3]	77	[3]
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets, Fair Value	68,471		44,524
Total financial liabilities, Fair Value	4,112		4,405
Carrying Value [Member] | Other assets, net [Member] | Marketable securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value	49,343	[1]	41,155	[1]
Carrying Value [Member] | Prepaid expenses and other current assets [Member] | Bank Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value			1,357	[2]
Carrying Value [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	212	[2]	23	[2]
Carrying Value [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	18,744	[2]	1,414	[2]
Carrying Value [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Put option contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value			152	[2]
Carrying Value [Member] | Prepaid expenses and other current assets [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	172	[2]	423	[2]
Carrying Value [Member] | Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	3,470	[3]	3,946	[3]
Carrying Value [Member] | Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	617	[3]	382	[3]
Carrying Value [Member] | Accounts payable and accrued liabilities [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	25	[3]	77	[3]
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets, Fair Value	49,343		42,512
Total financial liabilities, Fair Value	0		0
Level 1 [Member] | Other assets, net [Member] | Marketable securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value	49,343	[1]	41,155	[1]
Level 1 [Member] | Prepaid expenses and other current assets [Member] | Bank Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value			1,357	[2]
Level 1 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	0	[2]	0	[2]
Level 1 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	0	[2]	0	[2]
Level 1 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Put option contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value			0	[2]
Level 1 [Member] | Prepaid expenses and other current assets [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	0	[2]	0	[2]
Level 1 [Member] | Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	0	[3]	0	[3]
Level 1 [Member] | Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	0	[3]	0	[3]
Level 1 [Member] | Accounts payable and accrued liabilities [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	0	[3]	0	[3]
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets, Fair Value	19,128		2,012
Total financial liabilities, Fair Value	4,112		4,405
Level 2 [Member] | Other assets, net [Member] | Marketable securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value	0	[1]	0	[1]
Level 2 [Member] | Prepaid expenses and other current assets [Member] | Bank Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value			0	[2]
Level 2 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	212	[2]	23	[2]
Level 2 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	18,744	[2]	1,414	[2]
Level 2 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Put option contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value			152	[2]
Level 2 [Member] | Prepaid expenses and other current assets [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	172	[2]	423	[2]
Level 2 [Member] | Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	3,470	[3]	3,946	[3]
Level 2 [Member] | Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	617	[3]	382	[3]
Level 2 [Member] | Accounts payable and accrued liabilities [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	25	[3]	77	[3]
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets, Fair Value	0		0
Total financial liabilities, Fair Value	0		0
Level 3 [Member] | Other assets, net [Member] | Marketable securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value	0	[1]	0	[1]
Level 3 [Member] | Prepaid expenses and other current assets [Member] | Bank Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Assets, Fair Value			0	[2]
Level 3 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	0	[2]	0	[2]
Level 3 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	0	[2]	0	[2]
Level 3 [Member] | Prepaid expenses and other current assets [Member] | Cash flow hedging [Member] | Put option contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value			0	[2]
Level 3 [Member] | Prepaid expenses and other current assets [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	0	[2]	0	[2]
Level 3 [Member] | Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Precious metal forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	0	[3]	0	[3]
Level 3 [Member] | Accounts payable and accrued liabilities [Member] | Cash flow hedging [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	0	[3]	0	[3]
Level 3 [Member] | Accounts payable and accrued liabilities [Member] | Derivatives not designated as hedging instruments [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value	$ 0	[3]	$ 0	[3]

[1] Included within Other assets, net.

[2] Included within Prepaid expenses and other current assets.

[3] Included within Accounts payable and accrued liabilities.