Basis of Presentation - Summary of Disaggregation of Revenue by Segment and Product and Services (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Total revenues	$ 592,256	$ 517,474	$ 1,129,293	$ 956,343
Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	306,830	280,435	570,445	498,564
Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	285,426	237,039	558,848	457,779
Operating Segments [Member] | Satellite Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	205,717	162,962	402,532	316,523
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	205,717	162,962	402,532	316,523
Operating Segments [Member] | Commercial Networks [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	88,008	114,520	167,020	209,586
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	74,143	104,190	139,044	189,323
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	13,865	10,330	27,976	20,263
Operating Segments [Member] | Government Systems [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	298,531	239,992	559,741	430,234
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	232,687	176,245	431,401	309,241
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	$ 65,844	$ 63,747	$ 128,340	$ 120,993