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
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	$ 261,941		$ 9,568
Goodwill	181,737		122,300
Amortization of acquired intangible assets	5,929	$ 1,558
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	258,713		5,738
Goodwill	73,155		13,814
Amortization of acquired intangible assets	5,322	509
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting Information [Line Items]
Goodwill	44,083		44,044
Amortization of acquired intangible assets		257
Operating Segments [Member] | Government Systems [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	3,228		3,830
Goodwill	64,499		$ 64,442
Amortization of acquired intangible assets	$ 607	$ 792