Segment Information - Other Acquired Intangible Assets, Net and Goodwill Included in Segment Assets and Amortization of Acquired Intangible Assets by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2016
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	$ 44,552		$ 44,552		$ 33,604
Goodwill	119,625		119,625		117,040
Amortization of acquired intangible assets	2,775	$ 4,261	7,565	$ 13,658
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	23,556		23,556		8,751
Goodwill	13,434		13,434		9,809
Amortization of acquired intangible assets	1,605	2,488	3,814	8,018
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	5,314		5,314		6,581
Goodwill	43,892		43,892		43,990
Amortization of acquired intangible assets	411	706	1,267	1,957
Operating Segments [Member] | Government Systems [Member]
Segment Reporting Information [Line Items]
Other acquired intangible assets, net	15,682		15,682		18,272
Goodwill	62,299		62,299		$ 63,241
Amortization of acquired intangible assets	$ 759	$ 1,067	$ 2,484	$ 3,683