Financing Arrangements (Details) (USD $)	1 Months Ended		9 Months Ended								9 Months Ended					9 Months Ended			0 Months Ended	1 Months Ended			9 Months Ended		9 Months Ended			0 Months Ended	9 Months Ended			9 Months Ended
	Feb. 29, 2012 item	Apr. 30, 2013	Apr. 30, 2013 Minimum	Apr. 30, 2013 Maximum	Apr. 30, 2013 Lender's base rate	Apr. 30, 2013 LIBOR Minimum	Apr. 30, 2013 LIBOR Maximum	Apr. 30, 2013 New U.S. Credit Agreement	May 31, 2013 New U.S. Credit Agreement	Aug. 02, 2011 New U.S. Credit Agreement	Apr. 30, 2013 New U.S. Credit Agreement Minimum	Apr. 30, 2013 New U.S. Credit Agreement Maximum	Apr. 30, 2013 New U.S. Credit Agreement Lender's base rate	Apr. 30, 2013 New U.S. Credit Agreement Lender's base rate Minimum	Apr. 30, 2013 New U.S. Credit Agreement Lender's base rate Maximum	Apr. 30, 2013 New U.S. Credit Agreement LIBOR	Apr. 30, 2013 New U.S. Credit Agreement LIBOR Minimum	Apr. 30, 2013 New U.S. Credit Agreement LIBOR Maximum	May 31, 2013 Revolving Credit Facility	Aug. 31, 2011 Revolving Credit Facility	Apr. 30, 2013 Revolving Credit Facility	Aug. 02, 2011 Revolving Credit Facility	Apr. 30, 2013 Revolving Credit Facility Interest rate swap with fixed interest cash flows	Aug. 08, 2012 Revolving Credit Facility Interest rate swap with fixed interest cash flows	Apr. 30, 2013 Revolving Credit Facility One month LIBOR Interest rate swap with fixed interest cash flows	Aug. 02, 2011 Letters of credit	Aug. 02, 2011 Swing line loans	Aug. 02, 2011 Term Loan Facility	Apr. 30, 2013 Term Loan Facility item	Apr. 30, 2013 Term Loan Facility Interest rate swap with fixed interest cash flows	Aug. 08, 2012 Term Loan Facility Interest rate swap with fixed interest cash flows	Apr. 30, 2013 Term Loan Facility One month LIBOR Interest rate swap with fixed interest cash flows
Financing Arrangements
Maximum borrowing capacity										$ 150,000,000												$ 100,000,000				$ 20,000,000	$ 5,000,000
Borrowings																												50,000,000
Term of line of credit facility																				5 years
Maximum additional borrowing capacity available at the entity's option																				50,000,000
Unamortized debt issuance costs		839,000
Margin on reference rate (as a percent)													0.75%	0.25%	2.00%	1.75%	1.25%	3.00%
Reference rate, description			One month LIBOR	Twelve month LIBOR									lender's base rate			LIBOR									one month LIBOR							one month LIBOR
Reference rate (as a percent)					3.25%	0.20%	0.87%																		0.496%							0.664%
Fees on unused portion of credit facilities (as a percent)								0.30%			0.25%	0.50%
Number of existing senior lenders of debt, whose variable interest cash flows will be exchanged by the entity with fixed interest cash flows	1
Borrowing initially hedged																								25,000,000							40,000,000
Quarterly reduction in borrowings hedged																														2,500,000
Semi-annual reduction in borrowings hedged																							5,000,000
Number of quarterly principal installments																													20
Quarterly principal installments																													2,500,000
Mandatory prepayments of amounts outstanding as a percentage of net proceeds received from certain sales or other dispositions of all or any part of the entity and its subsidiaries' assets								100.00%
Mandatory prepayments of amounts outstanding as a percentage of certain insurance and condemnation proceeds received by the entity or any of its subsidiaries								100.00%
Mandatory prepayments of amounts outstanding as a percentage of net cash proceeds received from issuance or occurrence of any indebtedness of the entity or any of its subsidiaries								100.00%
Mandatory prepayments of amounts outstanding as a percentage of net proceeds from sale of certain equity								100.00%
Shares of foreign subsidiaries pledged as security (as a percent)								65.00%
Outstanding borrowings								105,000,000	100,000,000												72,500,000								32,500,000
Available borrowing capacity																					27,500,000
Repayment of borrowings																			$ 5,000,000