Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Operating Loss Carryforwards [Line Items]
Impairment charges	$ 46,867,000	$ 148,551,000	$ 204,448,000
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount	39,800,000	61,100,000	168,900,000
Unrecognized Tax Benefits	$ 21,133,000	17,849,000	37,575,000	$ 36,532,000
Foreign Net Operating Loss Carryforwards Expiration Dates
State Net Operating Loss Carryforwards Expiration Dates
Foreign Tax Credit Carryforward Expiration Dates
State Research And Development Tax Credit Carryforward Expiration Dates
Valuation Allowance, Deferred Tax Asset, Change in Amount	$ 2,513,000	$ 267,000
Effective Income Tax Rate Reconciliation, Tax Holidays		0.70%
Unrecognized Tax Benefits, Interest on Income Taxes Expense	157,000	$ 498,000	200,000
Unrecognized Tax Benefits, Income Tax Penalties Expense		25,000	313,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	1,531,000	1,739,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued	2,664,000
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	6,809,000
Unrecognized Tax Benefits Recognized In Other Liabilities	15,402,000	11,357,000
Reduction Of Longterm Deferred Income Tax Assets Excluding Interest and Penalties	5,731,000	6,492,000
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	905,000
Undistributed Earnings of Foreign Subsidiaries	353,300,000
Cash Held Outside the U.S.	95,983
Cash and cash equivalents	114,492,000	$ 81,834,000	$ 91,058,000	$ 305,900,000
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	126,293,000
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	92,250,000
Other Tax Carryforward, Gross Amount	22,812,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	54,731,000
Other Tax Carryforward, Gross Amount	11,178,000
Maximum recorded through earnings [Member]
Operating Loss Carryforwards [Line Items]
Unrecognized Tax Benefits, Income Tax Penalties Accrued	$ 6,809,000
United States, Federal [Member] | Low end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2013
United States, Federal [Member] | High end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2014
FRANCE | Low end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2013
FRANCE | High end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2014
GERMANY | Low end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2009
GERMANY | High end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2014
UNITED KINGDOM | Low end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2011
UNITED KINGDOM | High end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2014