Goodwill (Details)	3 Months Ended
	Oct. 31, 2017 USD ($) operating_segment	Aug. 01, 2017 $ / shares	Jul. 31, 2017 USD ($)
Goodwill [Line Items]
Goodwill	$ 290,633,000		$ 290,633,000
Number of reportable segments | operating_segment	2
Commercial Solutions Segment
Goodwill [Line Items]
Goodwill	$ 231,440,000		231,440,000
Reporting unit, percentage of fair value in excess of carrying amount		17.80%
Government Solutions Segment
Goodwill [Line Items]
Goodwill	$ 59,193,000		$ 59,193,000
Reporting unit, percentage of fair value in excess of carrying amount		52.90%
Common Stock
Goodwill [Line Items]
Common stock price (in dollars per share) | $ / shares		$ 18.47