Certain Balance Sheet Accounts - Summary of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Balance, beginning of year	$ 359	$ 155	$ 140
Provision for doubtful accounts	1,246	567	331
Write-offs	(977)	(363)	(316)
Balance, end of year	$ 628	$ 359	$ 155