The Company and a Summary of Its Significant Accounting Policies - Summary of Disaggregation of Revenue by Segment and Product and Services (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Disaggregation Of Revenue [Line Items]
Total revenues	$ 2,256,107	$ 2,309,238	$ 2,068,258
Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	1,044,450	1,172,541	1,092,691
Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	1,211,657	1,136,697	975,567
Operating Segments [Member] | Satellite Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	868,943	826,583	684,205
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	868,943	826,583	684,205
Operating Segments [Member] | Commercial Networks [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	320,856	344,557	428,404
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	268,830	289,959	383,547
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	52,026	54,598	44,857
Operating Segments [Member] | Government Systems [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	1,066,308	1,138,098	955,649
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	775,620	882,582	709,144
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	$ 290,688	$ 255,516	$ 246,505