Basis of Presentation - Summary of Disaggregation of Revenue by Segment and Product and Services (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Total revenues	$ 575,559	$ 588,224	$ 1,660,325	$ 1,717,517
Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	266,514	303,090	773,128	873,535
Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	309,045	285,134	887,197	843,982
Operating Segments [Member] | Satellite Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	220,789	211,700	638,660	614,232
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	220,789	211,700	638,660	614,232
Operating Segments [Member] | Commercial Networks [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	90,099	84,726	236,121	251,746
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	75,690	73,182	197,560	212,226
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	14,409	11,544	38,561	39,520
Operating Segments [Member] | Government Systems [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	264,671	291,798	785,544	851,539
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	190,824	229,908	575,568	661,309
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	$ 73,847	$ 61,890	$ 209,976	$ 190,230