Stockholders' Equity (Deficit) - Stock Options Activity and Stock-based Compensation (Details) - USD ($)
$ in Millions |
12 Months Ended |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Stock granted value, share-based compensation, gross |
$ 2.5
|
$ 39.9
|
$ 17.0
|
| Total grant-date fair value of awards vested |
10.8
|
9.7
|
1.7
|
| Total intrinsic value of options exercised |
25.3
|
31.1
|
$ 1.8
|
| Unrecognized compensation costs on non-vested stock options |
19.0
|
|
|
| Capitalized amount |
$ 0.3
|
|
|
| Stock Option [Member] |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Period of recognition for unrecognized compensation costs (in years) |
2 years 4 months 24 days
|
|
|
| Restricted Stock Units (RSUs) [Member] |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Stock granted value, share-based compensation, gross |
$ 47.1
|
$ 15.7
|
|
| Period of recognition for unrecognized compensation costs (in years) |
2 years 3 months 18 days
|
|
|
| Vested in period, fair value |
$ (3.2)
|
|
|
| Unrecognized compensation costs on non-vested restricted stock units |
$ 43.6
|
|
|