Stock-based Compensation - Summary of Restricted Stock Units (Detail) - $ / shares
|
12 Months Ended |
|
|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |
|
|
|
| Weighted-Average Grant Date Fair Value |
$ 3.40
|
$ 3.97
|
$ 3.31
|
| Time-Based Restricted Stock Units [Member] |
|
|
|
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |
|
|
|
| Number of Shares, Outstanding, Beginning Balance |
90,255
|
|
|
| Number of Shares, Granted |
366,004
|
|
|
| Number of Shares, Vested |
(90,255)
|
|
|
| Number of Shares, Outstanding, Ending Balance |
366,004
|
|
|
| Weighted-Average Grant Date Fair Value |
$ 6.63
|
6.66
|
|
| Weighted-Average Grant Date Fair Value, Granted |
6.63
|
|
|
| Weighted-Average Grant Date Fair Value, Vested |
$ 7.04
|
|
|
| Performance-Based Restricted Stock Units [Member] |
|
|
|
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |
|
|
|
| Number of Shares, Outstanding, Beginning Balance |
321,525
|
|
|
| Number of Shares, Granted |
340,094
|
|
|
| Number of Shares, Vested |
(137,127)
|
|
|
| Number of Shares, Forfeited or expired |
(25,123)
|
|
|
| Number of Shares, Outstanding, Ending Balance |
499,369
|
|
|
| Weighted-Average Grant Date Fair Value |
$ 6.66
|
$ 6.41
|
|
| Weighted-Average Grant Date Fair Value, Granted |
6.64
|
|
|
| Weighted-Average Grant Date Fair Value, Vested |
6.09
|
|
|
| Weighted-Average Grant Date Fair Value, Forfeited or expired |
$ 6.23
|
|
|