Senior Notes and Other Long-Term Debt - Components of Long-Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Mar. 31, 2023
Debt Instrument [Line Items]
Finance lease obligations (see Note 1)	$ 33,479	$ 36,405
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other long-term debt	Other long-term debt
Total debt	$ 7,593,834	$ 2,490,112
Unamortized discount and debt issuance costs	(315,783)	(30,672)
Less: current portion of long-term debt	59,757	37,939
Total long-term debt	7,218,294	2,421,501
2028 Notes [Member]
Debt Instrument [Line Items]
Principal amount of debt	400,000	400,000
2027 Notes [Member]
Debt Instrument [Line Items]
Principal amount of debt	600,000	600,000
2025 Notes [Member]
Debt Instrument [Line Items]
Principal amount of debt	700,000	700,000
Term Loan Facility [Member]
Debt Instrument [Line Items]
Principal amount of debt	693,000	694,750
Bridge Facility [Member]
Debt Instrument [Line Items]
Principal amount of debt	733,400
2023 Term Loan Facility [Member]
Debt Instrument [Line Items]
Principal amount of debt	616,700
Ex-Im Credit Facility [Member]
Debt Instrument [Line Items]
Principal amount of debt	49,130	$ 58,957
Inmarsat 2026 Notes [Member]
Debt Instrument [Line Items]
Principal amount of debt	2,075,000
Inmarsat Secured Credit Facility [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 1,693,125