v3.26.1
Fair Value Measurements - Additional Information (Detail) - USD ($)
3 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Satellite Performance Incentives Obligation [Member] | Satellites [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Expiration year of in-orbit satellite performance incentive obligation 2028  
Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities measured at fair value on a recurring basis $ 0 $ 0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Satellite Performance Incentives Obligation [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Satellite performance incentives obligation 4,900,000 6,100,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | 2027 Notes [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of long term debt 598,400,000 597,800,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | 2028 Notes [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of long term debt 399,000,000 395,000,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | 2031 Notes [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of long term debt 740,700,000 724,900,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Ex-Im Credit Facility [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of long term debt 173,200,000 186,200,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Inmarsat Senior Secured Notes 2029 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of long term debt $ 2,080,000,000.00 $ 2,070,000,000.00