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Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Debt - Additional Information (Detail) - USD ($) $ in Thousands		12 Months Ended
	Feb. 10, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Term loan and revolving line of credit paid		$ 14,840	$ 3,750	$ 6,142
SVB Agreement \| 2013 Capital Growth Term Loan \| Revolving Credit Facility
Debt Instrument [Line Items]
Term loan and revolving line of credit paid	$ 14,800