Long-Term Obligations - Additional Information (Details) - USD ($)	12 Months Ended			36 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2007	May. 13, 2010
Line of Credit Facilities [Line Items]
Proceeds from lines of credit	$ 83,382,000	$ 73,334,000	$ 231,613,000
Repayments on line of credit	32,314,000	62,398,000	181,000,000
Debt Instruments [Abstract]
Letters of credit outstanding	$ 3,327,000	3,634,000
Ratio Of debt to EBITDA	equal to 2.0 to 1.0
Interest expense coverage ratio	equal to 11.8 to 1.0
Long-term debt, fair value	$ 252,254,000	216,280,000
Long-term debt less notes payable	243,288,000	201,810,000
Private Placement [Member]
Debt Instruments [Abstract]
Debt face amount					$ 75,000,000.0
Debt instrument aggregate face amount during period				$ 350,000,000
Debt instrument, interest rate terms				from 5.30% to 5.33%
Repayments of long-term debt	$ 42,500,000	61,300,000
Euro-denominated notes payable in 2017 at a fixed rate of 3.71% [Member]
Debt Instruments [Abstract]
Debt face amount					30,000,000.0
Long-term debt, fixed interest rate percentage	3.71%
Euro-denominated notes payable in 2020 at a fixed rate of 4.24% [Member]
Debt Instruments [Abstract]
Debt face amount					$ 45,000,000.0
Long-term debt, fixed interest rate percentage	4.24%
USD-Denominated Borrowing Credit Revolver [Member]
Line of Credit Facilities [Line Items]
Line of credit, current borrowing capacity	$ 300,000,000
Line of credit, maximum borrowing capacity	450,000,000
Line of credit facility, maximum amount outstanding during period	114,000,000
Proceeds from lines of credit	60,000,000
Line of credit facility, amount outstanding	102,000,000
Line of credit, remaining borrowing capacity	194,673,000
Line of credit facility, maximum remaining borrowing capacity	$ 344,673,000
Line of credit facility, expiration date	Feb. 01, 2017
China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit, current borrowing capacity		$ 24,200,000	$ 26,200,000
Line of credit facility, maximum amount outstanding during period	$ 19,437,000
Repayments on line of credit	9,026,000
Line of credit facility, amount outstanding	10,411,000
Line of credit, remaining borrowing capacity	9,589,000
Lender 1 [Member] | China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit, current borrowing capacity	10,000
Lender 2 [Member] | China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit, current borrowing capacity	$ 10,000