Contingencies - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended			9 Months Ended	12 Months Ended
	Mar. 31, 2026	Oct. 31, 2025	Mar. 31, 2026	Dec. 31, 2025	Sep. 30, 2025	Dec. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2024
Loss Contingencies [Line Items]
Deferred revenues, long-term portion	$ 1,064,261		$ 1,064,261				$ 1,064,261	$ 786,710
Interest income							205,849	83,920	$ 96,258
Revenues							4,640,280	4,519,571	4,283,758
Ligado [Member]
Loss Contingencies [Line Items]
Revenues			16,000	$ 16,000	$ 16,000
Inmarsat [Member]
Loss Contingencies [Line Items]
Contingent and actual proceeds from legal settlements							$ 568,000
Contingent proceeds from legal settlements	100,000
Contingent legal settlement escalator							3.00%
Lump Sum | Ligado [Member]
Loss Contingencies [Line Items]
Proceeds from legal settlement		$ 420,000				$ 420,000
Deferred revenues, long-term portion	267,500		267,500				$ 267,500
Interest income							152,500
Product [Member]
Loss Contingencies [Line Items]
Revenues							1,365,857	1,293,795	1,279,164
Defense and Advanced Technologies [Member] | Positive Outcome of Litigation [Member] | Interest Income [Member]
Loss Contingencies [Line Items]
Revenues									7,200
Defense and Advanced Technologies [Member] | Positive Outcome of Litigation [Member] | Product [Member]
Loss Contingencies [Line Items]
Revenues							30,800	41,700	$ 99,900
Unfavorable Regulatory Action [Member]
Loss Contingencies [Line Items]
U.S. government contract-related reserves	$ 15,100		$ 15,100				$ 15,100	$ 14,800