Related Party Transactions - Additional Information (Detail) - Officer - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Consulting
Related Party Transaction [Line Items]
Transaction expenses incurred by parent company	$ 16,000	$ 14,000	$ 89,000	$ 111,000
Outstanding payables due to related party	4,000		4,000		$ 12,000
Software Licensing and Subscription
Related Party Transaction [Line Items]
Quarterly software licensing fee			200,000		200,000
Deferred costs related to annual software subscription	$ 84,000		$ 84,000		$ 50,500