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Lease Obligations - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Leases [Abstract]      
Rental expense $ 56,200,000 $ 53,400,000 $ 58,000,000
Property, plant and equipment under capital leases $ 0 $ 0