Segment Information - Segment Revenues and Operating Profits (Losses) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Revenues:
Total revenues	$ 2,256,107	$ 2,309,238	$ 2,068,258
Operating profits (losses):
Income (loss) from operations	58,233	38,421	(60,620)
Amortization of acquired intangible assets	(5,482)	(7,611)	(9,655)
Product [Member]
Revenues:
Total revenues	1,044,450	1,172,541	1,092,691
Service [Member]
Revenues:
Total revenues	1,211,657	1,136,697	975,567
Operating Segments [Member]
Operating profits (losses):
Income (loss) from operations	63,715	46,032	(50,965)
Operating Segments [Member] | Satellite Services [Member]
Revenues:
Total revenues	868,943	826,583	684,205
Operating profits (losses):
Income (loss) from operations	35,853	7,015	(64,321)
Amortization of acquired intangible assets	(2,164)	(2,897)	(4,857)
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Revenues:
Total revenues	868,943	826,583	684,205
Operating Segments [Member] | Commercial Networks [Member]
Revenues:
Total revenues	320,856	344,557	428,404
Operating profits (losses):
Income (loss) from operations	(180,749)	(186,877)	(166,613)
Amortization of acquired intangible assets	(257)	(1,539)	(1,542)
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Revenues:
Total revenues	268,830	289,959	383,547
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Revenues:
Total revenues	52,026	54,598	44,857
Operating Segments [Member] | Government Systems [Member]
Revenues:
Total revenues	1,066,308	1,138,098	955,649
Operating profits (losses):
Income (loss) from operations	208,611	225,894	179,969
Amortization of acquired intangible assets	(3,061)	(3,175)	(3,256)
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Revenues:
Total revenues	775,620	882,582	709,144
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Revenues:
Total revenues	290,688	255,516	246,505
Material Reconciling Items [Member]
Operating profits (losses):
Amortization of acquired intangible assets	$ (5,482)	$ (7,611)	$ (9,655)