Long-Term Obligations - Additional Information (Details) € in Millions	12 Months Ended			36 Months Ended
	Jul. 31, 2018 USD ($) Rate	Jul. 31, 2017 USD ($)	Jul. 31, 2016 USD ($)	Jul. 31, 2007 USD ($)	May 13, 2010 USD ($)	May 13, 2010 EUR (€)
Line of Credit Facilities [Line Items]
Repayments on line of credit	$ (78,419,000)	$ (244,268,000)	$ (91,759,000)
Debt Instruments [Abstract]
Letters of credit outstanding	$ 3,043,000	4,067,000
Ratio Of debt to EBITDA	equal to 0.3 to 1.0
Interest expense coverage ratio	equal to 58.7 to 1.0
Long-term debt, fair value	$ 55,707,000	109,303,000
Long-term debt less notes payable	52,618,000	$ 104,536,000
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
Euro-denominated notes payable in 2017 at a fixed rate of 3.71% [Member]
Debt Instruments [Abstract]
Debt face amount | €						€ 30.0
Long-term debt, fixed interest rate percentage | Rate	3.71%
Euro-denominated notes payable in 2020 at a fixed rate of 4.24% [Member]
Debt Instruments [Abstract]
Debt face amount | €						€ 45.0
Long-term debt, fixed interest rate percentage | Rate	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	57,235,000
Repayments on line of credit	(51,941,000)
Line of credit, remaining borrowing capacity	296,957,000
Line of credit facility, maximum remaining borrowing capacity	446,957,000
China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit facility, maximum amount outstanding during period	3,228,000
Repayments on line of credit	(3,257,000)
Line of credit, remaining borrowing capacity	10,000,000
Lender 1 [Member] | China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit, current borrowing capacity	$ 10,000,000