Stock-Based Compensation - Stock Appreciation Rights (Details) - Stock Appreciation Rights - $ / shares
|
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Number of SAR’s |
|
|
|
| Awards outstanding, beginning balance (in shares) |
2,396,126
|
1,809,302
|
1,373,069
|
| Granted (in shares) |
176,824
|
655,855
|
449,225
|
| Exercised (in shares) |
(8,003)
|
(14,470)
|
(435)
|
| Forfeited (in shares) |
(56,932)
|
(54,561)
|
(12,557)
|
| Awards outstanding, ending balance (in shares) |
2,508,015
|
2,396,126
|
1,809,302
|
| Number of SAR's - SAR's exercisable (in shares) |
1,015,440
|
|
|
| Number of SAR's - SAR's expected to vest (in shares) |
1,096,639
|
|
|
| Weighted Average Exercise Price (in dollars per share) |
|
|
|
| SAR's outstanding - beginning balance (in dollars per share) |
$ 10.33
|
$ 10.63
|
$ 10.28
|
| Granted (in dollars per share) |
8.80
|
9.47
|
11.73
|
| Exercised (in dollars per share) |
8.57
|
9.21
|
7.37
|
| Forfeited (in dollars per share) |
10.75
|
10.30
|
11.57
|
| SAR's outstanding - ending balance (in dollars per share) |
10.22
|
$ 10.33
|
$ 10.63
|
| Weighted Average Exercise Price - SAR's exercisable (in dollars per share) |
15.92
|
|
|
| Weighted Average Exercise Price - SAR's expected to vest (in dollars per share) |
$ 10.19
|
|
|
| Weighted Average Contractual Term - SAR's outstanding |
6 years 8 months 12 days
|
7 years 7 months 6 days
|
8 years 1 month 6 days
|
| Weighted Average Contractual Term - SAR's expected to vest |
6 years 8 months 12 days
|
|
|