Quarterly report pursuant to Section 13 or 15(d)

Equity-Based Compensation - Summary of Equity Grants (Detail)

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Equity-Based Compensation - Summary of Equity Grants (Detail) (USD $)
9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Performance Shares
   
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Beginning Balance, Units 238,371 257,787
Granted, Units 0 0
Vested, Units (140,549)  
Forfeited, Units (851) (13,121)
Ending Balance, Units 96,971 244,666
Beginning Balance, Fair Value per unit $ 3.75 $ 3.27
Granted, Fair Value per unit $ 0 $ 0
Vested, Fair Value per unit $ 0  
Forfeited, Fair Value per unit   $ (3.75)
Ending Balance, Fair Value per unit $ 3.75 $ 3.75
Deferred Equity Units
   
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Beginning Balance, Units 175,298 329,757
Granted, Units 0 0
Vested, Units (123,110) (133,863)
Forfeited, Units   (4,066)
Ending Balance, Units 52,188 191,828
Deferred Equity Units | Minimum
   
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Beginning Balance, Fair Value per unit $ 12.00  
Granted, Fair Value per unit $ 0 $ 0
Vested, Fair Value per unit $ (12.00)  
Ending Balance, Fair Value per unit $ 12.00 $ 12.00
Deferred Equity Units | Maximum
   
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Beginning Balance, Fair Value per unit $ 17.05 $ 10.47
Granted, Fair Value per unit $ 0 $ 0
Vested, Fair Value per unit $ (16.81) $ (12.00)
Forfeited, Fair Value per unit   $ (12.00)
Ending Balance, Fair Value per unit $ 13.62 $ 13.63