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	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	$ 9,568	$ 14,439
Goodwill	122,300	121,197
Amortization of acquired intangible assets	5,482	7,611	$ 9,655
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	5,738	7,368
Goodwill	13,814	13,489
Amortization of acquired intangible assets	2,164	2,897	4,857
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net		257
Goodwill	44,044	43,981
Amortization of acquired intangible assets	257	1,539	1,542
Operating Segments [Member] | Government Systems [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	3,830	6,814
Goodwill	64,442	63,727
Amortization of acquired intangible assets	$ 3,061	$ 3,175	$ 3,256