Summary of Operations and Significant Accounting Policies - Summary of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Allowance for doubtful accounts, beginning balance	$ 268	$ 291	$ 242
Charges to expense	(115)	116	103
Write-offs of uncollectible accounts, net of recoveries	(75)	(139)	(54)
Allowance for doubtful accounts, ending balance	$ 78	$ 268	$ 291