Long-Term Obligations (Details Textual)	12 Months Ended			36 Months Ended															12 Months Ended			1 Months Ended
	Jul. 31, 2011 USD ($)	Jul. 31, 2010 USD ($)	Jul. 31, 2009 USD ($)	Jul. 31, 2007 USD ($) PrivatePlacement	Oct. 05, 2006 USD ($) Banks	May 13, 2010 Senior Unsecured Notes [Member] EUR (€)	Jul. 31, 2011 Euro-denominated notes payable in 2017 at a fixed rate of 3.71% [Member] USD ($)	Jul. 31, 2010 Euro-denominated notes payable in 2017 at a fixed rate of 3.71% [Member] USD ($)	May 13, 2010 Euro-denominated notes payable in 2017 at a fixed rate of 3.71% [Member] EUR (€)	Jul. 31, 2011 Euro-denominated notes payable in 2020 at a fixed rate of 4.24%[Member] USD ($)	Jul. 31, 2010 Euro-denominated notes payable in 2020 at a fixed rate of 4.24%[Member] USD ($)	May 13, 2010 Euro-denominated notes payable in 2020 at a fixed rate of 4.24%[Member] EUR (€)	Jul. 31, 2011 USD-denominated notes payable through 2014 at a fixed rate of 5.14% [Member] USD ($)	Jul. 31, 2010 USD-denominated notes payable through 2014 at a fixed rate of 5.14% [Member] USD ($)	Jul. 31, 2011 USD-denominated notes payable through 2016 at a fixed rate of 5.30%[Member] USD ($)	Jul. 31, 2010 USD-denominated notes payable through 2016 at a fixed rate of 5.30%[Member] USD ($)	Jul. 31, 2011 USD-denominated notes payable through 2017 at a fixed rate of 5.33% [Member] USD ($)	Jul. 31, 2010 USD-denominated notes payable through 2017 at a fixed rate of 5.33% [Member] USD ($)	Jul. 31, 2011 Senior Unsecured Notes Prepayment Penalties [Member] USD ($)	Jul. 31, 2010 Senior Unsecured Notes Prepayment Penalties [Member] USD ($)	Jul. 31, 2009 Senior Unsecured Notes Prepayment Penalties [Member] USD ($)	Jun. 30, 2009 Senior Unsecured Notes Without Penalty [Member] USD ($)	Jul. 31, 2011 Line of Credit [Member] USD ($)	Jul. 31, 2010 Line of Credit [Member] USD ($)	Oct. 05, 2006 Line of Credit [Member]
Long-Term Obligations (Textuals) [Abstract]
Aggregate principal amount of senior unsecured notes under private placement						€ 75,000,000			€ 30,000,000			€ 45,000,000
Interest rate on senior notes							3.71%			4.24%			5.14%		5.30%		5.33%
Debt to EBITDA	1.7 to 1.0																						equal to 1.8 to 1.0		not more than a 3.0 to 1.0
Scheduled principal payments	61,264,000	44,893,000	87,224,000																61,300,000	44,900,000	21,400,000	65,800,000
EBIT to interest expense ratio related to debt agreement	equal to 7.8 to 1.0																								not less than a 3.0 to 1.0
Outstanding letters of credit																							1,466,000	1,564,000
Total number of Private placement from 2004 to 2007				3
Aggregate principal amount of private placement note issuances in ten-year fixed rate notes with varying maturity dates				500,000,000
Interest rate on total private placement note				from 5.14% to 5.33%
Debt Instrument, Payment Terms	repaid equally over seven years, with initial payment due dates ranging from 2008 to 2011, with interest payable
Interest payable on notes	semianually
Interest payment starts	December 2004
Multi-currency revolving loan agreement					200,000,000
Number of Banks under multi-currency revolving loan agreement					5
Increased available amount under the credit facility					300,000,000
Interest rate terms option under the credit agreement	either a base interest rate -based upon the higher of the federal funds rate plus one-half of 1% or the prime rate of Bank of America) or a Eurocurrency interest rate -at the LIBOR rate plus a margin based on the Company’s consolidated leverage ratio)
Payment restriction					annually to $50 million plus an amount equal to 75% of consolidated net income for the prior fiscal year of the Company
Extended amendment maturity date to the revolving loan agreement	from October 5, 2011 to March 18, 2013
Long Term Debt Obligation at Fair Value	416,694,000	467,479,000
Long Term Debt Obligation at Carrying Value	$ 393,178,000	$ 444,204,000					$ 43,194,000	$ 45,615,000		$ 64,791,000	$ 52,132,000		$ 56,250,000	$ 75,000,000	$ 130,714,000	$ 156,857,000	$ 98,229,000	$ 114,600,000