Acquisitions (Narrative) (Details)								2 Months Ended	3 Months Ended		5 Months Ended	9 Months Ended		12 Months Ended
	Jun. 01, 2020	May 31, 2020 USD ($)	Apr. 30, 2020 USD ($)	Feb. 21, 2020 USD ($)	Jan. 27, 2020 USD ($) $ / shares shares	Apr. 29, 2019 USD ($) employee	Feb. 28, 2019 USD ($) shares	Jul. 31, 2020 USD ($)	Apr. 30, 2020 USD ($)	Apr. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) $ / shares	Apr. 30, 2020 USD ($)	Apr. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Jan. 29, 2020 USD ($)	Jul. 31, 2019 USD ($)
Business Acquisition [Line Items]
Revenue									$ 135,121,000	$ 170,448,000		$ 467,042,000	$ 495,425,000
Operating income									(3,136,000)	$ 11,296,000		12,358,000	$ 31,002,000
Cash and cash equivalents			$ 50,634,000						50,634,000			50,634,000				$ 45,576,000
Debt			159,400,000						159,400,000			159,400,000				$ 165,000,000
Gilat
Business Acquisition [Line Items]
Revenue														$ 263,492,000
Operating income														25,572,000
Cash and cash equivalents														74,778,000
Debt														$ 8,096,000
Secured Credit Facility
Business Acquisition [Line Items]
Secured credit facility, maximum borrowing capacity			550,000,000						$ 550,000,000			$ 550,000,000
Secured Credit Facility | Forecast
Business Acquisition [Line Items]
Secured credit facility, maximum borrowing capacity								$ 800,000,000
Solacom
Business Acquisition [Line Items]
Aggregate purchase price							$ 32,934,000
Aggregate purchase price - settled in cash							27,328,000
Aggregate purchase price - settled with issuance of common stock							$ 5,606,000
Aggregate purchase price - settled with issuance of common stock (in shares) | shares							208,669
Consideration transferred, net of cash acquired							$ 31,489,000
Cash acquired from acquisition							$ 1,445,000
GD NG-911 business
Business Acquisition [Line Items]
Aggregate purchase price						$ 11,013,000
Development contract term						5 years
Number of employees hired | employee						60
CGC Technology
Business Acquisition [Line Items]
Aggregate purchase price			23,650,000		$ 23,650,000
Aggregate purchase price - settled in cash			12,075,000		12,075,000
Aggregate purchase price - settled with issuance of common stock			$ 11,575,000		$ 11,575,000
Aggregate purchase price - settled with issuance of common stock (in shares) | shares					323,504
Consideration transferred, net of cash acquired					$ 22,740,000
Cash acquired from acquisition					$ 160,000
Weighted average stock price (in dollars per share) | $ / shares					$ 35.78
Payable subject to closing conditions					$ 750,000
UHP Networks | Forecast
Business Acquisition [Line Items]
Aggregate purchase price								38,000,000
Aggregate purchase price - settled in cash								$ 5,000,000
Gilat
Business Acquisition [Line Items]
Enterprise value															$ 532,500,000
Gilat | Forecast
Business Acquisition [Line Items]
Consideration, cash, per share (in usd per share) | $ / shares											$ 7.18
Consideration, shares, share issuance ratio											0.08425
Transaction related costs, capitalized and expensed											$ 31,678,000
NG-911
Business Acquisition [Line Items]
Aggregate purchase price				$ 1,188,000
Aggregate purchase price - settled in cash				781,000
Earn out additional payable				$ 407,000
Earn out additional payable, term				5 years
Subsequent Event | UHP Networks
Business Acquisition [Line Items]
Percent reduction in previously agreed-upon purchase price	24.00%
Previously agreed-upon purchase price		$ 50,000,000