The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Jul. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 2,900	$ 3,800
Amortized intangibles:
Accumulated amortization	(45,309)		$ (42,025)
Net intangibles	62,897		64,892
Covenants not to compete
Amortized intangibles:
Gross carrying amount	1,668		1,666
Supply contracts & customer relationships
Amortized intangibles:
Gross carrying amount	73,105		71,787
Trade name
Amortized intangibles:
Gross carrying amount	24,092		24,173
Licenses and databases
Amortized intangibles:
Gross carrying amount	$ 9,341		$ 9,291