Revenue - Summary of Opening and Closing Balances of Company's Receivables and Current and Long-term Contract Liabilities (Detail) - Accounting Standards Update 2014-09 [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Trade Receivables	$ 170,175
Contract liabilities-current	5,314
Contract liabilities-noncurrent	6,540
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Trade Receivables		$ 150,151
Contract liabilities-current		5,736
Contract liabilities-noncurrent		$ 5,222
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Trade Receivables	20,024
Contract liabilities-current	(422)
Contract liabilities-noncurrent	$ 1,318