Balance Sheet Classification of Contingent Consideration Liability (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Business Combination, Transactions [Line Items]
Other accrued liabilities	$ 404	$ 759
Other accrued liabilities
Business Combination, Transactions [Line Items]
Other accrued liabilities	36	329
Other long-term liabilities
Business Combination, Transactions [Line Items]
Other accrued liabilities	$ 368	$ 430