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Accounts Payable, Accrued Expenses and Other Long-Term Liabilities - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Accounts Payable and Accrued Liabilities [Line Items]    
Workers' compensation and auto liability $ 26.3 $ 21.4
Workers' compensation discount rate 3.00% 3.00%
Workers compensation and auto liability, undiscounted basis $ 29.4 $ 23.9