Stock-based Compensation - Performance Stock Unit Activity (Detail) - Performance Stock Units [Member] - $ / shares
|
12 Months Ended |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] |
|
|
|
| Number of Stock Units, Beginning balance (in shares) |
229,170
|
61,321
|
80,000
|
| Number of Stock Units, Granted (in shares) |
59,221
|
186,705
|
63,895
|
| Number of Stock Units, Vested and converted to common stock (in shares) |
(13,397)
|
(9,429)
|
0
|
| Number of Stock Units, Forfeited (in shares) |
(2,970)
|
(9,427)
|
(82,574)
|
| Number of Stock Units, Ending balance (in shares) |
272,024
|
229,170
|
61,321
|
| Weighted- Average Grant-date Fair Value |
|
|
|
| Weighted-Average Grant-date Fair Value, Beginning balance (in dollars per share) |
$ 17.06
|
$ 19.77
|
$ 23.75
|
| Weighted-Average Grant-date Fair Value, Granted (in dollars per share) |
23.64
|
17.19
|
13.89
|
| Weighted-Average Grant-date Fair Value, Vested and converted to common stock (in dollars per share) |
20.62
|
27.18
|
0.00
|
| Weighted-Average Grant-date Fair Value, Forfeited (in dollars per share) |
20.62
|
27.18
|
19.07
|
| Weighted-Average Grant-date Fair Value, Ending balance (in dollars per share) |
$ 18.28
|
$ 17.06
|
$ 19.77
|