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Equity-Based Compensation (Performance Units to be Settled in Common Stock) - Additional Information (Detail) - Performance Units [Member] - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Required performance period 3 years    
Performance units vesting conditions These performance units cliff-vest at the end of a three-year performance period based on achievement of three-year company financial performance targets and strategic initiatives established by the Compensation Committee.    
Performance units granted 300,000 200,000 100,000
Granted, weighted average grant date fair value, per share $ 22.86 $ 28.16 $ 35.20
Compensation costs $ 3.2 $ 3.6 $ 2.4
Performance units vested 0 0 0
Number of common shares issued in connection with performance units 0 0 0
Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance units performance percentage 0.00%    
Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance units performance percentage 200.00%