Satellite Network and Other Equipment, Net - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) OG2Satellite	Sep. 30, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Property Plant And Equipment [Line Items]
Depreciation and amortization expense			$ 49,684,000	$ 45,681,000	$ 42,803,000
Non-cash impairment charge				31,224,000	10,680,000
Products and Services and Internal-use Software [Member]
Property Plant And Equipment [Line Items]
Company capitalized internal costs attributable to design, development and enhancements of Company's products and services and internal-use software			12,817,000	12,776,000	9,786,000
Fixed Assets [Member]
Property Plant And Equipment [Line Items]
Depreciation and amortization expense			$ 36,609,000	$ 33,889,000	$ 30,465,000
Depreciation and amortization expense percentage related to cost of services			47.00%	61.00%	69.00%
Depreciation and amortization expense percentage related to cost of product sales			9.00%	8.00%	10.00%
Internal-use Software [Member]
Property Plant And Equipment [Line Items]
Amortization of internal-use software			$ 3,433,000	$ 6,186,000	$ 3,545,000
OG2 Satellite [Member]
Property Plant And Equipment [Line Items]
Non-cash impairment charge	$ 31,224,000	$ 10,680,000	$ 0	$ 31,224,000	$ 10,680,000
Number of satellite loss of communication | OG2Satellite	3
Removal/decrease in satellite network and other equipment, net	$ 39,576,000	13,474,000
Accumulated depreciation on equipment	$ (8,352,000)	$ (2,794,000)