Commitments and Contingencies - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) plaintiff	Dec. 31, 2015 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Additional capital lease agreement		$ 105	$ 0	$ 105
Rental expenses included in general and administrative expenses	$ 727	$ 681	1,500	$ 1,400
Refunds paid to certain subscribers					$ 63	$ 1,200
Number of plaintiffs | plaintiff					661
Contract obligation future minimum non-refundable total payment	1,000		$ 1,000
Contract obligation future minimum non-refundable payment end date			Jun. 30, 2020
Accrual for state taxes	$ 995		$ 995