Basis of Presentation - Summary of Disaggregation of Revenue by Segment and Product and Services (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Total revenues	$ 530,488	$ 537,037
Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	250,634	263,615
Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	279,854	273,422
Operating Segments [Member] | Satellite Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	201,984	196,815
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	201,984	196,815
Operating Segments [Member] | Commercial Networks [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	67,162	79,012
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	55,119	64,901
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	12,043	14,111
Operating Segments [Member] | Government Systems [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	261,342	261,210
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	195,515	198,714
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	$ 65,827	$ 62,496