Long-Term Obligations - Additional Information (Details) € in Millions	12 Months Ended			36 Months Ended
	Jul. 31, 2017 USD ($) Rate	Jul. 31, 2016 USD ($)	Jul. 31, 2015 USD ($)	Jul. 31, 2007 USD ($)	May 13, 2010 USD ($)	May 13, 2010 EUR (€)
Line of Credit Facilities [Line Items]
Proceeds from lines of credit	$ 180,320,000	$ 96,276,000	$ 83,382,000
Repayments on line of credit	244,268,000	91,759,000	$ 32,314,000
Debt Instruments [Abstract]
Letters of credit outstanding	$ 4,067,000	4,261,000
Ratio Of debt to EBITDA	equal to 0.7 to 1.0
Interest expense coverage ratio	equal to 30.6 to 1.0
Long-term debt, fair value	$ 109,303,000	218,977,000
Long-term debt less notes payable	104,536,000	$ 211,982,000
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	112,000,000
Proceeds from lines of credit	60,666,000
Line of credit, remaining borrowing capacity	244,599,000
Line of credit facility, maximum remaining borrowing capacity	394,599,000
China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit facility, maximum amount outstanding during period	5,691,000
Repayments on line of credit	(1,700,000)
Line of credit facility, amount outstanding	3,228,000
Line of credit, remaining borrowing capacity	6,772,000
Lender 1 [Member] | China line of credit facility [Member]
Line of Credit Facilities [Line Items]
Line of credit, current borrowing capacity	$ 10,000