Segment Information - Segment Revenues and Operating Profits (Losses) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Revenues:
Total revenues	$ 2,309,238	$ 2,068,258	$ 1,594,625
Operating profits (losses):
Income (loss) from operations	38,421	(60,620)	(92,187)
Amortization of acquired intangible assets	(7,611)	(9,655)	(12,231)
Product [Member]
Revenues:
Total revenues	1,172,541	1,092,691	755,547
Service [Member]
Revenues:
Total revenues	1,136,697	975,567	839,078
Operating Segments [Member]
Operating profits (losses):
Income (loss) from operations	46,032	(50,965)	(79,956)
Operating Segments [Member] | Satellite Services [Member]
Revenues:
Total revenues	826,583	684,205	589,287
Operating profits (losses):
Income (loss) from operations	7,015	(64,321)	12,018
Amortization of acquired intangible assets	(2,897)	(4,857)	(7,622)
Operating Segments [Member] | Satellite Services [Member] | Product [Member]
Revenues:
Total revenues			664
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Revenues:
Total revenues	826,583	684,205	588,623
Operating Segments [Member] | Commercial Networks [Member]
Revenues:
Total revenues	344,557	428,404	233,221
Operating profits (losses):
Income (loss) from operations	(186,877)	(166,613)	(229,105)
Amortization of acquired intangible assets	(1,539)	(1,542)	(1,563)
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Revenues:
Total revenues	289,959	383,547	198,034
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Revenues:
Total revenues	54,598	44,857	35,187
Operating Segments [Member] | Government Systems [Member]
Revenues:
Total revenues	1,138,098	955,649	772,117
Operating profits (losses):
Income (loss) from operations	225,894	179,969	137,131
Amortization of acquired intangible assets	(3,175)	(3,256)	(3,046)
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Revenues:
Total revenues	882,582	709,144	556,849
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Revenues:
Total revenues	255,516	246,505	215,268
Material Reconciling Items [Member]
Operating profits (losses):
Amortization of acquired intangible assets	$ (7,611)	$ (9,655)	$ (12,231)