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, 2020	Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Total revenues	$ 2,309,238	$ 2,068,258	$ 1,594,625
Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	1,172,541	1,092,691	755,547
Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	1,136,697	975,567	839,078
Operating Segments [Member] | Satellite Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	826,583	684,205	589,287
Operating Segments [Member] | Satellite Services [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues			664
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	826,583	684,205	588,623
Operating Segments [Member] | Commercial Networks [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	344,557	428,404	233,221
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	289,959	383,547	198,034
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	54,598	44,857	35,187
Operating Segments [Member] | Government Systems [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	1,138,098	955,649	772,117
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	882,582	709,144	556,849
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	$ 255,516	$ 246,505	$ 215,268