Segment Information - Segment Revenues and Operating Profits (Losses) (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Product revenues	$ 169,574	$ 156,290	$ 517,485	$ 488,298
Income (loss) from operations	7,591	10,385	33,783	33,625
Operating Segments [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	10,366	14,646	41,348	47,283
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Product revenues	7,114	6,453	20,581	19,105
Income (loss) from operations	34,846	21,772	98,263	59,849
Operating Segments [Member] | Implied License [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Product revenues	6,800	6,400	20,000	18,800
Income (loss) from operations	$ 6,800	$ 6,400	$ 20,000	$ 18,800