Fair Value Measurements - Additional Information (Detail) - USD ($)	6 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2017
Satellite Performance Incentives Obligation [Member] | ViaSat-1 and ViaSat-2 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
2025 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal amount of senior notes issued	$ 700,000,000.0		$ 700,000,000.0
2027 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal amount of senior notes issued	600,000,000.0	$ 600,000,000.0
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on a recurring basis	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Satellite Performance Incentives Obligation [Member] | ViaSat-1 and ViaSat-2 Satellites [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Satellite performance incentives obligation	27,900,000	28,200,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | 2025 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long term debt	705,100,000	670,300,000
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	630,800,000
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	$ 127,300,000	$ 134,900,000