Summary of Significant Accounting Policies (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax, Beginning Balance	$ (1,154)	$ (321)	$ (53)
Accumulated Other Comprehensive Income (Loss), Defined Benefit Pension and Other Postretirement Plans, Net of Tax, Beginning Balance	2,188	1,357	1,942
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax, Beginning Balance	112,864	49,869	51,162
Accumulated other comprehensive income, Beginning Balance	113,898	50,905	53,051
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax, Ending Balance	876	(1,154)	(321)
Accumulated Other Comprehensive Income (Loss), Defined Benefit Pension and Other Postretirement Plans, Net of Tax, Ending Balance	978	2,188	1,357
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax, Ending Balance	57,557	112,864	49,869
Accumulated other comprehensive income, Ending Balance	59,411	113,898	50,905
Unrealized (loss) gain on cash flow hedges	2,030	(833)	(268)
Amortization of (gain) loss on post-retirement medical plans	(1,210)	831	(585)
Foreign currency translation adjustments	(55,307)	62,995	(1,293)
Total comprehensive income (loss)	$ (72,398)	$ 171,645	$ 79,810