Equity Compensation (Restricted Stock Units) (Details) - USD ($)
$ / shares in Units, $ in Millions |
12 Months Ended |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
| Weighted Average Grant Date Fair Value |
|
|
|
| Aggregate intrinsic value of unvested restricted stock |
$ 38.4
|
|
|
| Common stock price (in dollars per share) |
$ 29.76
|
|
|
| Restricted stock units |
|
|
|
| Restricted stock units |
|
|
|
| Non-vested balance at beginning of period (in shares) |
1,396,387
|
425,000
|
|
| Awarded |
783,060
|
1,147,946
|
433,000
|
| Vested |
(823,620)
|
(35,340)
|
|
| Forfeited |
(65,167)
|
(141,219)
|
(8,000)
|
| Non-vested balance at end of period (in shares) |
1,290,660
|
1,396,387
|
425,000
|
| Weighted Average Grant Date Fair Value |
|
|
|
| Non-vested balance at beginning of period (in dollars per share) |
$ 7.60
|
$ 8.18
|
|
| Awarded (in dollars per share) |
11.28
|
7.40
|
$ 8.18
|
| Vested (in dollars per share) |
7.62
|
7.85
|
|
| Forfeited (in dollars per share) |
8.82
|
7.66
|
8.18
|
| Non-vested balance at end of period (in dollars per share) |
$ 9.75
|
$ 7.60
|
$ 8.18
|
| Total fair value of awards vested |
$ 16.0
|
$ 0.4
|
|
| Shares withheld for tax purposes (in shares) |
284,329
|
|
|
| Issuance of shares net of shares withheld (in shares) |
539,291
|
|
|