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, 2020	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	$ 14,439	$ 22,301
Goodwill	121,197	121,719
Amortization of acquired intangible assets	7,611	9,655	$ 12,231
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	7,368	10,453
Goodwill	13,489	13,617
Amortization of acquired intangible assets	2,897	4,857	7,622
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	257	1,798
Goodwill	43,981	43,933
Amortization of acquired intangible assets	1,539	1,542	1,563
Operating Segments [Member] | Government Systems [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	6,814	10,050
Goodwill	63,727	64,169
Amortization of acquired intangible assets	$ 3,175	$ 3,256	$ 3,046