Segment Information - Segment Revenues and Operating Profits (Losses) (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Product revenues	$ 175,957	$ 169,574	$ 523,858	$ 517,485
Income (loss) from operations	(25,326)	7,591	(59,136)	33,783
Operating Segments [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	(22,149)	10,366	(49,379)	41,348
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Product revenues	233	7,114	664	20,581
Income (loss) from operations	$ 1,681	34,846	$ 33,140	98,263
Operating Segments [Member] | Implied License [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Product revenues		6,800		20,000
Income (loss) from operations		$ 6,800		$ 20,000