Defined Contribution Plan - Additional Information (Detail)	12 Months Ended
Dec. 31, 2016 USD ($)
Compensation And Retirement Disclosure [Abstract]
Matching contributions made	$ 0

Amount of discretionary contributions made by an employer to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration