Fair Value Measurements - Additional Information (Detail) - USD ($)	6 Months Ended
	Sep. 30, 2017	Sep. 21, 2017	Mar. 31, 2017
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		$ 96,000
2020 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal amount of senior notes issued		$ 575,000,000	575,000,000
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	$ 700,000,000
Satellite Performance Incentives Obligation [Member] | ViaSat-1 Satellite [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest on in-orbit satellite performance incentive obligation	7.00%
Period of in-orbit satellite performance incentive obligation	15 years
Level 1 [Member] | 2020 Notes [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long term debt			587,900,000
Level 2 [Member] | 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			96,000
Satellite performance incentives obligation	$ 21,500,000		21,800,000
Level 2 [Member] | Fair Value, Measurements, Recurring [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	$ 356,900,000		$ 297,200,000