Goodwill (Details)	6 Months Ended
Jan. 31, 2021 USD ($) operating_segment	Aug. 01, 2020 $ / shares
Goodwill [Roll Forward]
Balance as of July 31, 2020	$ 330,519,000
Change related to CGC acquisition	2,222,000
Change related to Solacom Technologies Inc. ("Solacom")	1,052,000
Balance as of January 31, 2021	$ 333,793,000
Number of operating segments \| operating_segment	2
Common Stock
Goodwill [Roll Forward]
Share price (in dollars per share) \| $ / shares		$ 16.42
Commercial Solutions
Goodwill [Roll Forward]
Balance as of July 31, 2020	$ 255,432,000
Change related to CGC acquisition	0
Change related to Solacom Technologies Inc. ("Solacom")	1,052,000
Balance as of January 31, 2021	256,484,000
Percentage of fair value in excess of carrying amount for reporting unit		8.40%
Government Solutions
Goodwill [Roll Forward]
Balance as of July 31, 2020	75,087,000
Change related to CGC acquisition	2,222,000
Change related to Solacom Technologies Inc. ("Solacom")	0
Balance as of January 31, 2021	$ 77,309,000
Percentage of fair value in excess of carrying amount for reporting unit		78.00%

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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