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Commitments and Contingencies - Collective Bargaining Agreements (Detail) - Withdrawal from Multiemployer Defined Benefit Plan - Central States Plan - USD ($)
$ in Millions
1 Months Ended 55 Months Ended
Dec. 31, 2017
Dec. 31, 2017
Jan. 31, 2016
Jul. 31, 2014
Oct. 09, 2013
Loss Contingencies [Line Items]          
Final settlement amount $ 48.9 $ 48.9      
Amount of withdrawal liability 44.1 44.1 $ 32.9 $ 39.6  
Interest on assessed amount of withdrawal liability 4.8 4.8      
Payment of withdrawal liability assessment amount $ 25.5        
Acquired Company          
Loss Contingencies [Line Items]          
Amount of withdrawal liability     $ 4.8   $ 4.8
Payment of withdrawal liability assessment amount   $ 4.2      
Amount of withdrawal liability, amount suggested by Plan which is different than amount recorded by company         $ 6.9