Segment Information - Segment Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 5,349,467	$ 4,883,868
Operating Segments [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	702,771	758,758
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	64,048	86,252
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	168,334	188,269
Operating Segments [Member] | Government Systems [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	470,389	484,237
Corporate, Non-Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 4,646,696	$ 4,125,110