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, 2020	Jun. 30, 2019	Mar. 31, 2020
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	$ 13,041		$ 14,439
Goodwill	121,285		121,197
Amortization of acquired intangible assets	1,558	$ 2,037
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	7,024		7,368
Goodwill	13,620		13,489
Amortization of acquired intangible assets	509	855
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net			257
Goodwill	44,021		43,981
Amortization of acquired intangible assets	257	386
Operating Segments [Member] | Government Systems [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	6,017		6,814
Goodwill	63,644		$ 63,727
Amortization of acquired intangible assets	$ 792	$ 796