Notes Payable - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Apr. 30, 2013	Apr. 30, 2013	Apr. 30, 2012	Jul. 31, 2012
Line of Credit Facility [Line Items]
Repayment of borrowing on notes payable		$ 173,000	$ 0
Weighted average borrowing rate	1.20%	1.20%
Remaining borrowing capacity	253,000	253,000
Line of Credit Facility, Maximum Borrowing Capacity	403,000	403,000
Outstanding balance on credit facility	58,658	58,658		0
Proceeds from borrowing on notes payable	220,000	220,000	0
USD-denominated credit facility China [Member]
Line of Credit Facility [Line Items]
Remaining borrowing capacity	14,542	14,542
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Outstanding balance on credit facility	$ 47,000	$ 47,000