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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Paragraph 1
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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 20
-Section 50
-Paragraph 1
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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Percentage of fair value of reporting unit in excess of carrying amount.

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Price of a single share of a number of saleable stocks of a company.

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Goodwill (Details)	9 Months Ended
Goodwill (Details)	Apr. 30, 2019 USD ($) operating_segment	Aug. 01, 2018 $ / shares
Goodwill [Roll Forward]
Goodwill	$ 290,633,000
Goodwill	$ 310,247,000
Number of reportable segments \| operating_segment	2
Commercial Solutions Segment
Goodwill [Roll Forward]
Goodwill	$ 231,440,000
Goodwill	251,054,000
Reporting unit, percentage of fair value in excess of carrying amount		42.50%
Government Solutions Segment
Goodwill [Roll Forward]
Goodwill	59,193,000
Goodwill	59,193,000
Reporting unit, percentage of fair value in excess of carrying amount		105.50%
Common Stock
Goodwill [Roll Forward]
Common stock price (in dollars per share) \| $ / shares		$ 33.7
Solacom Technologies Inc
Goodwill [Roll Forward]
Addition resulting from acquisition	11,964,000
Solacom Technologies Inc \| Commercial Solutions Segment
Goodwill [Roll Forward]
Addition resulting from acquisition	11,964,000
Solacom Technologies Inc \| Government Solutions Segment
Goodwill [Roll Forward]
Addition resulting from acquisition	0
GD 911 business
Goodwill [Roll Forward]
Addition resulting from acquisition	7,650,000
GD 911 business \| Commercial Solutions Segment
Goodwill [Roll Forward]
Addition resulting from acquisition	7,650,000
GD 911 business \| Government Solutions Segment
Goodwill [Roll Forward]
Addition resulting from acquisition	$ 0