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Segment Information - Segment Revenues and Operating Profits (Losses) (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Income (loss) from operations	$ (60,620)	$ (92,187)	$ 36,459
TrellisWare [Member]
Segment Reporting Information [Line Items]
Minority interest ownership percentage by parent			52.00%	52.00%
Operating Segments [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	(50,965)	(79,956)	$ 47,247
Operating Segments [Member] \| Satellite Services [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	(64,321)	12,018	131,085
Operating Segments [Member] \| Government Systems [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	$ 179,969	$ 137,131	96,658
Uncharacterized damages and penalties			11,800
Operating Segments [Member] \| Implied License [Member] \| Satellite Services [Member] \| Product [Member]
Segment Reporting Information [Line Items]
Product revenues			26,800
Income (loss) from operations			$ 26,800