Intangible Assets (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019	Jul. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 414,733,000		$ 414,733,000		$ 400,509,000
Accumulated amortization	154,571,000		154,571,000		138,619,000
Net carrying amount	260,162,000		260,162,000		$ 261,890,000
Amortization of intangibles	5,517,000	$ 4,536,000	15,952,000	$ 13,113,000
Amortization expense - year one	21,445,000		21,445,000
Amortization expense - year two	21,040,000		21,040,000
Amortization expense - year three	19,458,000		19,458,000
Amortization expense - year four	19,458,000		19,458,000
Amortization expense - year five	18,766,000		$ 18,766,000
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period			20 years 5 months		20 years 6 months
Gross carrying amount	284,558,000		$ 284,558,000		$ 276,834,000
Accumulated amortization	76,205,000		76,205,000		66,484,000
Net carrying amount	208,353,000		$ 208,353,000		$ 210,350,000
Technologies
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period			13 years 8 months 12 days		12 years 8 months 12 days
Gross carrying amount	97,649,000		$ 97,649,000		$ 92,649,000
Accumulated amortization	63,866,000		63,866,000		59,522,000
Net carrying amount	33,783,000		$ 33,783,000		$ 33,127,000
Trademarks and other
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period			16 years 7 months 12 days		16 years 8 months 12 days
Gross carrying amount	32,526,000		$ 32,526,000		$ 31,026,000
Accumulated amortization	14,500,000		14,500,000		12,613,000
Net carrying amount	$ 18,026,000		$ 18,026,000		$ 18,413,000