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Other - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Other [Line Items]      
Depreciation charge $ 8,000 $ 6,600 $ 8,000
Accumulated depreciation and amortization 112,468 104,817  
Assets Held under Capital Leases      
Other [Line Items]      
Machinery, furniture and equipment 1,800 2,000  
Accumulated depreciation and amortization $ 1,700 $ 1,900