Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Operating Loss Carryforwards [Line Items]
Impairment charges	$ 0	$ 46,867,000	$ 148,551,000
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount		39,800,000	61,100,000
Unrecognized Tax Benefits	$ 15,294,000	21,133,000	17,849,000	$ 37,575,000
Foreign Net Operating Loss Carryforwards Expiration Dates	eight years
State Net Operating Loss Carryforwards Expiration Dates	2017 to 2034
Foreign Tax Credit Carryforward Expiration Dates	2021 to 2025
State Research And Development Tax Credit Carryforward Expiration Dates	2017 to 2031
Valuation Allowance, Deferred Tax Asset, Change in Amount	$ 1,930,000	2,513,000
Unrecognized Tax Benefits, Interest on Income Taxes Expense	3,000	157,000	498,000
Unrecognized Tax Benefits, Income Tax Penalties Expense	0		25,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	1,530,000	1,531,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued	2,730,000	3,000
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	3,878,000
Unrecognized Tax Benefits Recognized In Other Liabilities	9,304,000	15,402,000
Reduction Of Longterm Deferred Income Tax Assets Excluding Interest and Penalties	5,990,000	5,731,000
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	428,000
Undistributed Earnings of Foreign Subsidiaries	259,334,000
Cash Held Outside the U.S.	139,747
Cash and cash equivalents	141,228,000	$ 114,492,000	$ 81,834,000	$ 91,058,000
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	119,874,000
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	89,637,000
Other Tax Carryforward, Gross Amount	14,381,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	42,095,000
Other Tax Carryforward, Gross Amount	11,526,000
Maximum recorded through earnings [Member]
Operating Loss Carryforwards [Line Items]
Unrecognized Tax Benefits, Income Tax Penalties Accrued	$ 3,878,000
United States, Federal [Member] | Low end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2015
United States, Federal [Member] | High end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2016
FRANCE | Low end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2012
FRANCE | High end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2016
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	2016
UNITED KINGDOM | Low end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2014
UNITED KINGDOM | High end of range [Member]
Operating Loss Carryforwards [Line Items]
Open Tax Year	2016