Fair Value Measurements - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended					3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended							3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended							3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jul. 31, 2012	Jan. 31, 2013 Other Assets [Member]	Jul. 31, 2012 Other Assets [Member]	Jul. 31, 2012 Prepaid expenses and other current assets [Member]	Jan. 31, 2013 Prepaid expenses and other current assets [Member]	Jul. 31, 2012 Other current liabilities [Member]	Jan. 31, 2013 Other current liabilities [Member]	Jan. 31, 2013 Long term obligations less current maturities [Member]	Jul. 31, 2012 Long term obligations less current maturities [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 1 [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 1 [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 1 [Member] Other Assets [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 1 [Member] Other Assets [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 1 [Member] Prepaid expenses and other current assets [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 1 [Member] Prepaid expenses and other current assets [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 1 [Member] Other current liabilities [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 1 [Member] Other current liabilities [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 1 [Member] Long term obligations less current maturities [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 1 [Member] Long term obligations less current maturities [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 2 [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 2 [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 2 [Member] Other Assets [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 2 [Member] Other Assets [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 2 [Member] Prepaid expenses and other current assets [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 2 [Member] Prepaid expenses and other current assets [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 2 [Member] Other current liabilities [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 2 [Member] Other current liabilities [Member]	Jan. 31, 2013 Fair Value, Inputs, Level 2 [Member] Long term obligations less current maturities [Member]	Jul. 31, 2012 Fair Value, Inputs, Level 2 [Member] Long term obligations less current maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities				$ 13,864	$ 12,676									$ 13,864	$ 12,676									$ 0	$ 0
Foreign exchange contracts	(83)	(3,228)				1,234	817	281	584							0	0	0	0							1,234	817	281	584
Total Assets	14,681		13,910									13,864	12,676									817	1,234
Foreign currency denominated debt	457,283		338,668							108,064	99,081									0	0									108,064	99,081
Total Liabilities	$ 108,648		$ 99,362									$ 0	$ 0									$ 108,648	$ 99,362