Consolidated Financial Statement Components - Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Supplemental Balance Sheet Information [Abstract]
Accrued network costs, asset retirement obligations and other	$ 3,055	$ 2,173
Accrued outside services	1,400	2,437
Total other current liabilities	$ 4,455	$ 4,610