Intangible Assets (Details) - USD ($)
 3 Months Ended 9 Months Ended 12 Months Ended
Apr. 30, 2017
Apr. 30, 2016
Apr. 30, 2017
Apr. 30, 2016
Jul. 31, 2016
Finite-Lived Intangible Assets [Line Items]          
Gross carrying amount $ 361,095,000   $ 361,095,000   $ 361,095,000
Accumulated amortization 93,956,000   93,956,000   76,401,000
Net carrying amount 267,139,000   267,139,000   $ 284,694,000
Amortization of intangibles 5,468,000 $ 4,776,000 17,555,000 $ 7,348,000  
Amortization expense - year one 22,823,000   22,823,000    
Amortization expense - year two 21,075,000   21,075,000    
Amortization expense - year three 17,155,000   17,155,000    
Amortization expense - year four 17,155,000   17,155,000    
Amortization expense - year five 16,196,000   $ 16,196,000    
Customer Relationships          
Finite-Lived Intangible Assets [Line Items]          
Weighted average amortization period     20 years 3 months 18 days   20 years 3 months 18 days
Gross carrying amount 249,831,000   $ 249,831,000   $ 249,831,000
Accumulated amortization 38,567,000   38,567,000   28,497,000
Net carrying amount 211,264,000   $ 211,264,000   $ 221,334,000
Technologies          
Finite-Lived Intangible Assets [Line Items]          
Weighted average amortization period     12 years 3 months 18 days   12 years 3 months 18 days
Gross carrying amount 82,370,000   $ 82,370,000   $ 82,370,000
Accumulated amortization 47,182,000   47,182,000   42,860,000
Net carrying amount 35,188,000   $ 35,188,000   $ 39,510,000
Trademarks and other          
Finite-Lived Intangible Assets [Line Items]          
Weighted average amortization period     16 years 4 months 22 days   16 years 3 months 18 days
Gross carrying amount 28,894,000   $ 28,894,000   $ 28,894,000
Accumulated amortization 8,207,000   8,207,000   5,044,000
Net carrying amount $ 20,687,000   $ 20,687,000   $ 23,850,000