Segment Information - Segment Revenues and Operating Profits (Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Total revenues	$ 530,488	$ 537,037
Operating profits (losses):
Loss from operations	(5,314)	(8,065)
Amortization of acquired intangible assets	(1,558)	(2,037)
Product [Member]
Revenues:
Total revenues	250,634	263,615
Service [Member]
Revenues:
Total revenues	279,854	273,422
Operating Segments [Member]
Operating profits (losses):
Loss from operations	(3,756)	(6,028)
Operating Segments [Member] | Satellite Services [Member]
Revenues:
Total revenues	201,984	196,815
Operating profits (losses):
Loss from operations	(1,857)	(2,070)
Amortization of acquired intangible assets	(509)	(855)
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Revenues:
Total revenues	201,984	196,815
Operating Segments [Member] | Commercial Networks [Member]
Revenues:
Total revenues	67,162	79,012
Operating profits (losses):
Loss from operations	(51,394)	(49,861)
Amortization of acquired intangible assets	(257)	(386)
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Revenues:
Total revenues	55,119	64,901
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Revenues:
Total revenues	12,043	14,111
Operating Segments [Member] | Government Systems [Member]
Revenues:
Total revenues	261,342	261,210
Operating profits (losses):
Loss from operations	49,495	45,903
Amortization of acquired intangible assets	(792)	(796)
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Revenues:
Total revenues	195,515	198,714
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Revenues:
Total revenues	65,827	62,496
Material Reconciling Items [Member]
Operating profits (losses):
Amortization of acquired intangible assets	$ (1,558)	$ (2,037)