Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Receivables [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Valuation and qualifying accounts, beginning balance	$ 1,233	$ 706	$ 279
Charged to costs and expenses	310	669	403
Charged to other accounts	486	142	24
Valuation and qualifying accounts, ending balance	1,057	1,233	706
Deferred Tax Asset Valuation Allowance [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Valuation and qualifying accounts, beginning balance	20,200	12,913	11,235
Charged to costs and expenses	12,350	7,287	1,718
Charged to other accounts			(40)
Valuation and qualifying accounts, ending balance	$ 32,550	$ 20,200	$ 12,913