Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2016	Mar. 31, 2016
2020 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal amount of senior notes issued	$ 575,000	$ 575,000
Satellite Performance Incentives Obligation [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 including interest	15 years
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Satellite performance incentives obligation and accrued interest	$ 22,000	22,000
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	300,800	219,900
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	$ 592,300	$ 597,300