Senior Notes and Other Long-Term Debt - Senior Notes (Detail) - USD ($) $ in Millions		1 Months Ended				12 Months Ended
	Sep. 28, 2023	Jun. 30, 2020	Oct. 31, 2019	Mar. 31, 2019	Sep. 30, 2017	Mar. 31, 2024
2031 Notes [Member]
Debt Instrument [Line Items]
Principal amount of senior notes issued	$ 733.4
Debt maturity year	2031
Interest rate on the outstanding borrowings	7.50%
2031 Notes [Member] | Debt Instrument, Redemption, Other Period One [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						Prior to May 30, 2026, the Company may redeem up to 40% of the 2031 Notes at a redemption price of 107.500% of the principal amount thereof, plus accrued and unpaid interest, if any, thereon to the redemption date, from the net cash proceeds of specified equity offerings.
Redemption price percentage of Senior Notes						107.50%
2031 Notes [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						The Company may also redeem the 2031 Notes prior to May 30, 2026, in whole or in part, at a redemption price equal to 100% of the principal amount thereof plus a “make whole” premium and any accrued and unpaid interest, if any, thereon to the redemption date.
Redemption price percentage of Senior Notes						100.00%
2031 Notes [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						The 2031 Notes may be redeemed, in whole or in part, at any time during the 12 months beginning on May 30, 2026 at a redemption price of 103.750%
Redemption price percentage of Senior Notes						103.75%
2031 Notes [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						during the 12 months beginning on May 30, 2027 at a redemption price of 101.875%
Redemption price percentage of Senior Notes						101.875%
2031 Notes [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						after May 30, 2028 at a redemption price of 100%, in each case plus accrued and unpaid interest, if any, thereon to the redemption date.
Redemption price percentage of Senior Notes						100.00%
2031 Notes [Member] | Change of Control [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						In the event a change of control triggering event occurs (as defined in the indenture governing the 2031 Notes), each holder will have the right to require the Company to repurchase all or any part of such holder’s 2031 Notes at a purchase price in cash equal to 101% of the aggregate principal amount of the 2031 Notes repurchased, plus accrued and unpaid interest, if any, to the date of purchase (subject to the right of holders of record on the relevant record date to receive interest due on the relevant interest payment date).
Redemption price percentage of Senior Notes						101.00%
2028 Notes [Member]
Debt Instrument [Line Items]
Principal amount of senior notes issued		$ 400.0
Debt maturity year		2028
Interest rate on the outstanding borrowings		6.50%
2028 Notes [Member] | Debt Instrument, Redemption, Other Period One [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						in whole or in part, at any time during the 12 months beginning on July 15, 2023 at a redemption price of 103.250%
Redemption price percentage of Senior Notes						103.25%
2028 Notes [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						during the 12 months beginning on July 15, 2024 at a redemption price of 101.625%
Redemption price percentage of Senior Notes						101.625%
2028 Notes [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						at any time on or after July 15, 2025 at a redemption price of 100%, in each case plus accrued and unpaid interest, if any, thereon to the redemption date.
Redemption price percentage of Senior Notes						100.00%
2028 Notes [Member] | Change of Control [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						In the event a change of control triggering event occurs (as defined in the indenture governing the 2028 Notes), each holder will have the right to require the Company to repurchase all or any part of such holder’s 2028 Notes at a purchase price in cash equal to 101% of the aggregate principal amount of the 2028 Notes repurchased, plus accrued and unpaid interest, if any, to the date of purchase (subject to the right of holders of record on the relevant record date to receive interest due on the relevant interest payment date).
Redemption price percentage of Senior Notes						101.00%
2027 Notes [Member]
Debt Instrument [Line Items]
Principal amount of senior notes issued				$ 600.0
Debt maturity year				2027
Interest rate on the outstanding borrowings				5.625%
2027 Notes [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						in whole or in part, at any time at a redemption price of 100% plus accrued and unpaid interest, if any, thereon to the redemption date.
2027 Notes [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption price percentage of Senior Notes						100.00%
2027 Notes [Member] | Change of Control [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						In the event a change of control triggering event occurs (as defined in the indenture governing the 2027 Notes), each holder will have the right to require the Company to repurchase all or any part of such holder’s 2027 Notes at a purchase price in cash equal to 101% of the aggregate principal amount of the 2027 Notes repurchased, plus accrued and unpaid interest, if any, to the date of purchase (subject to the right of holders of record on the relevant record date to receive interest due on the relevant interest payment date).
Redemption price percentage of Senior Notes						101.00%
2025 Notes [Member]
Debt Instrument [Line Items]
Principal amount of senior notes issued					$ 700.0
Debt maturity year					2025
Interest rate on the outstanding borrowings					5.625%
2025 Notes [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						in whole or in part, at any time at a redemption price of 100% plus accrued and unpaid interest, if any, thereon to the redemption date.
2025 Notes [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						at any time at a redemption price of 100% plus accrued and unpaid interest, if any, thereon to the redemption date.
Redemption price percentage of Senior Notes						100.00%
2025 Notes [Member] | Change of Control [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						In the event a change of control triggering event occurs (as defined in the indenture governing the 2025 Notes), each holder will have the right to require the Company to repurchase all or any part of such holder’s 2025 Notes at a purchase price in cash equal to 101% of the aggregate principal amount of the 2025 Notes repurchased, plus accrued and unpaid interest, if any, to the date of purchase (subject to the right of holders of record on the relevant record date to receive interest due on the relevant interest payment date).
Redemption price percentage of Senior Notes						101.00%
Inmarsat Senior Secured Notes Two Thousand And Twenty Six [Member]
Debt Instrument [Line Items]
Principal amount of senior notes issued			$ 2,080.0
Debt maturity year			2026
Interest rate on the outstanding borrowings			6.75%
Inmarsat Senior Secured Notes Two Thousand And Twenty Six [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						in whole or in part, at any time
Inmarsat Senior Secured Notes Two Thousand And Twenty Six [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						during the 12 months beginning on October 1, 2023 at a redemption price of 101.688%
Redemption price percentage of Senior Notes						101.688%
Inmarsat Senior Secured Notes Two Thousand And Twenty Six [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						and at any time on or after October 1, 2024 at a redemption price of 100%, in each case plus accrued and unpaid interest, if any, thereon to the redemption date.
Redemption price percentage of Senior Notes						100.00%
Inmarsat Senior Secured Notes Two Thousand And Twenty Six [Member] | Change of Control [Member]
Debt Instrument [Line Items]
Redemption description of Senior Notes						In the event a change of control occurs (as defined in the indenture governing the Inmarsat 2026 Notes), each holder will have the right to require Inmarsat to repurchase all or any part of such holder’s Inmarsat 2026 Notes at a purchase price in cash equal to 101% of the aggregate principal amount of the Inmarsat 2026 Notes repurchased, plus accrued and unpaid interest, if any, to the date of purchase (subject to the right of holders of record on the relevant record date to receive interest due on the relevant interest payment date). The consummation of the Inmarsat Acquisition did not give rise to a “change of control” under the indenture governing the Inmarsat 2026 Notes.
Redemption price percentage of Senior Notes						101.00%