Quarterly report pursuant to Section 13 or 15(d)

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

v3.3.0.814
Equity-Based Compensation - Summary of Equity Grants (Detail) - $ / shares
9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Performance Units    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Beginning Balance, Units 96,971 238,371
Vested, Units (90,585) (140,549)
Forfeited, Units   (851)
Ending Balance, Units 6,386 96,971
Beginning Balance, Range of Fair Value per unit $ 3.75 $ 3.75
Ending Balance, Range of Fair Value per unit $ 3.75 $ 3.75
Deferred Compensation Share Based Payments    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Beginning Balance, Units 52,188 175,298
Vested, Units (47,277) (123,110)
Ending Balance, Units 4,911 52,188
Deferred Compensation Share Based Payments | Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Beginning Balance, Range of Fair Value per unit $ 12.00 $ 12.00
Vested, Range of Fair Value per unit (12.00) (12.00)
Ending Balance, Range of Fair Value per unit 12.00 12.00
Deferred Compensation Share Based Payments | Maximum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Beginning Balance, Range of Fair Value per unit 15.65 17.05
Vested, Range of Fair Value per unit (13.97) (16.81)
Ending Balance, Range of Fair Value per unit $ 10.81 $ 13.62