Commitments and Contingencies - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) plaintiff	Dec. 31, 2015 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Additional capital lease agreement	$ 0	$ 137
Rental expenses included in general and administrative expenses	743	$ 712
Refunds paid to certain subscribers			$ 63	$ 1,200
Number of plaintiffs | plaintiff			661
Contract obligation future minimum non-refundable total payment	$ 886
Contract obligation future minimum non-refundable payment end date	Dec. 31, 2018