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Inventories - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Inventory Disclosure [Abstract]        
Amounts credited to the allowance for obsolete inventory $ 0.2 $ 0.6 $ 0.3 $ 0.8