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Stock-based Compensation - Summary of PSU Activity (Detail) (Potential Performance Shares (PSU)) - Performance Share Units (PSU)
 12 Months Ended
Dec. 31, 2016
Unit
$ / EquityUnit
Dec. 31, 2015
Unit
$ / EquityUnit
Dec. 31, 2014
Unit
$ / EquityUnit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Beginning Balance, Number of Units, Outstanding | Unit 133,931    
Number of Units, Granted | Unit 60,015 94,250 37,792
Number of Units, Earned | Unit (7,540)    
Number of Units, Unearned or forfeited | Unit (51,756)    
Ending Balance, Number of Units, Outstanding | Unit 134,650 133,931  
Beginning Balance, Weighted Average Grant Price, Outstanding | $ / EquityUnit 45.27    
Weighted Average Grant Price, Granted | $ / EquityUnit 7.00 7.30 99.05
Weighted Average Grant Price, Earned | $ / EquityUnit 21.90    
Weighted Average Grant Price, Unearned or forfeited | $ / EquityUnit 64.40    
Ending Balance, Weighted Average Grant Price, Outstanding | $ / EquityUnit 22.17 45.27