Consolidated Financial Statement Components - Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Supplemental Balance Sheet Information [Abstract]
Accrued outside services	$ 999	$ 975
Accrued network costs	630	773
Accrued accounting and legal	277	467
Asset retirement obligations	235	85
Deferred rent and other	44	433
Total other current liabilities	$ 2,185	$ 2,733