Satellite Network and Other Equipment - Summary of Satellite Network and Other Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Satellite network and other equipment, gross	$ 263,949	$ 286,434
Less: accumulated depreciation and amortization	(87,845)	(70,593)
Satellite network and other equipment, net	176,104	215,841
Land [Member]
Property Plant And Equipment [Line Items]
Satellite network and other equipment, gross	381	381
Satellite Network [Member]
Property Plant And Equipment [Line Items]
Satellite network and other equipment, gross	193,358	231,782
Capitalized Software [Member]
Property Plant And Equipment [Line Items]
Satellite network and other equipment, gross	42,243	30,758
Computer Hardware [Member]
Property Plant And Equipment [Line Items]
Satellite network and other equipment, gross	5,245	4,707
Other [Member]
Property Plant And Equipment [Line Items]
Satellite network and other equipment, gross	7,974	7,522
Assets under Construction [Member]
Property Plant And Equipment [Line Items]
Satellite network and other equipment, gross	$ 14,748	$ 11,284