Segment Information - Segment Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Mar. 31, 2021
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 6,086,794	$ 5,349,467
Operating Segments [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,143,662	702,771
Operating Segments [Member] | Satellite Services [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	437,337	64,048
Operating Segments [Member] | Commercial Networks [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	228,416	168,334
Operating Segments [Member] | Government Systems [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	477,909	470,389
Corporate, Non-Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 4,943,132	$ 4,646,696