Segment Information - Segment Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 2,491,249	$ 2,397,312
Operating Segments [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	565,522	582,399
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	60,687	57,529
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	184,190	212,943
Operating Segments [Member] | Government Systems [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	320,645	311,927
Corporate, Non-Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,925,727	$ 1,814,913