Segment Information - Segment Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 4,904,374	$ 4,883,868
Operating Segments [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	717,034	758,758
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	79,180	86,252
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	177,768	188,269
Operating Segments [Member] | Government Systems [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	460,086	484,237
Corporate, Non-Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 4,187,340	$ 4,125,110