Satellite Network and Other Equipment - Additional Information (Detail) $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Aug. 31, 2016 USD ($)	Sep. 30, 2017 USD ($) OG2Satellite	Sep. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Property Plant And Equipment [Line Items]
Non-cash impairment charge		$ 31,224	$ 10,680		$ 31,224	$ 10,680
Products and Services [Member]
Property Plant And Equipment [Line Items]
Company capitalized internal costs attributable to the design, development and enhancements of the company's products and services		3,232	2,215		9,840	6,947
Fixed Assets [Member]
Property Plant And Equipment [Line Items]
Depreciation expense		$ 8,850	$ 8,048		$ 25,891	$ 22,429
Depreciation and amortization expense percentage related to cost of services		61.00%	72.00%		63.00%	69.00%
Depreciation and amortization expense percentage related to cost of product sales		8.00%	7.00%		8.00%	10.00%
Internal-use Software [Member]
Property Plant And Equipment [Line Items]
Depreciation expense		$ 1,602	$ 889		$ 4,437	$ 2,534
Satellite Network [Member]
Property Plant And Equipment [Line Items]
Impairment loss on asset				$ 466
AIS Satellites [Member]
Property Plant And Equipment [Line Items]
Decrease in satellite network and other equipment, net				2,374
Accumulated depreciation on equipment				$ 1,908
OG2 Satellite [Member]
Property Plant And Equipment [Line Items]
Decrease in satellite network and other equipment, net					39,576	13,474
Accumulated depreciation on equipment					$ 8,352	$ 2,794
Non-cash impairment charge	$ 10,680	$ 31,224
Number of satellite loss of communication | OG2Satellite		3
OG1 Plane D Satellites [Member]
Property Plant And Equipment [Line Items]
Decrease in satellite network and other equipment, net							$ 137
Accumulated depreciation on equipment							$ 137