Segment Information - Segment Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 5,994,533	$ 5,349,467
Operating Segments [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,156,993	702,771
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	449,976	64,048
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	235,575	168,334
Operating Segments [Member] | Government Systems [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	471,442	470,389
Corporate, Non-Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 4,837,540	$ 4,646,696