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Quarterly Financial Data (Unaudited) - Narrative (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]          
Asset impairment charges $ 58,100   $ 58,057 $ 7,964 $ 58,451
Asset impairment charges, net of tax $ 36,600 $ 7,100      
Impairment of long-lived assets to be disposed of   $ 8,000   $ 8,000