Segment Information - Other Acquired Intangible Assets, Net and Goodwill Included in Segment Assets and Amortization of Acquired Intangible Assets by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2021
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	$ 243,331		$ 243,331		$ 9,568
Goodwill	191,125		191,125		122,300
Amortization of acquired intangible assets	7,399	$ 1,300	13,328	$ 2,858
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	240,419		240,419		5,738
Goodwill	82,764		82,764		13,814
Amortization of acquired intangible assets	7,097	546	12,419	1,055
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting Information [Line Items]
Goodwill	44,067		44,067		44,044
Amortization of acquired intangible assets				257
Operating Segments [Member] | Government Systems [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	2,912		2,912		3,830
Goodwill	64,294		64,294		$ 64,442
Amortization of acquired intangible assets	$ 302	$ 754	$ 909	$ 1,546