Equity-based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions | 3 Months Ended | 9 Months Ended |
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015 |
LTIP | | | | |
Compensation agreement | | | | |
Compensation expense recognized | $ 9.2 | $ 13.9 | $ 30.4 | $ 62.4 |
Tax benefit | 3 | 4.7 | 9.9 | 21.1 |
Tax shortfall related to equity-based compensation | 1 | 0.1 | 5.3 | 18.5 |
Fair value of awards vested | $ 2.4 | $ 1 | $ 13.4 | $ 51.8 |
Other disclosures | | | | |
Number of shares remaining available for grant | 8,300 | | 8,300 | |
Minimum | LTIP | | | | |
Equity-based Compensation | | | | |
Vesting period | | | 3 years | |
Maximum | LTIP | | | | |
Equity-based Compensation | | | | |
Vesting period | | | 4 years | |
Service Vesting Restricted Stock Awards | LTIP | | | | |
Outstanding unvested awards activity | | | | |
Outstanding at the beginning of the period (in shares) | | | 810 | |
Vested (in shares) | | | (322) | |
Outstanding at the end of the period (in shares) | 488 | | 488 | |
Weighted-Average Grant-Date Fair Value | | | | |
Outstanding at beginning of the period (in dollars per share) | | | $ 9.20 | |
Vested (in dollars per share) | | | 9.77 | |
Outstanding at the end of the period (in dollars per share) | $ 8.83 | | $ 8.83 | |
Market/Service Vesting Restricted Stock Awards | LTIP | | | | |
Outstanding unvested awards activity | | | | |
Outstanding at the beginning of the period (in shares) | | | 261 | |
Forfeited (in shares) | | | (162) | |
Vested (in shares) | | | (99) | |
Weighted-Average Grant-Date Fair Value | | | | |
Outstanding at beginning of the period (in dollars per share) | | | $ 9.44 | |
Forfeited (in dollars per share) | | | 9.44 | |
Vested (in dollars per share) | | | 9.44 | |
Market/Service Vesting Restricted Stock Awards | Minimum | LTIP | | | | |
Weighted-Average Grant-Date Fair Value for awards | | | | |
Granted (in dollars per share) | | | 6.70 | |
Weighted-Average Grant-Date Fair Value | | | | |
Granted (in dollars per share) | | | $ 6.70 | |
Significant assumptions used to calculate fair values | | | | |
Expected volatility (as a percent) | | | 41.30% | |
Risk-free interest rate (as a percent) | | | 0.50% | |
Market/Service Vesting Restricted Stock Awards | Maximum | LTIP | | | | |
Weighted-Average Grant-Date Fair Value for awards | | | | |
Granted (in dollars per share) | | | $ 13.57 | |
Weighted-Average Grant-Date Fair Value | | | | |
Granted (in dollars per share) | | | $ 13.57 | |
Significant assumptions used to calculate fair values | | | | |
Expected volatility (as a percent) | | | 56.70% | |
Risk-free interest rate (as a percent) | | | 1.10% | |
Other disclosures | | | | |
Vesting percentage of the awards granted | | | 100.00% | |
Service Vesting Restricted Stock Units | LTIP | | | | |
Weighted-Average Grant-Date Fair Value for awards | | | | |
Granted (in dollars per share) | | | $ 4.05 | |
Outstanding unvested awards activity | | | | |
Outstanding at the beginning of the period (in shares) | | | 3,592 | |
Granted (in shares) | | | 2,152 | |
Forfeited (in shares) | | | (131) | |
Vested (in shares) | | | (1,378) | |
Outstanding at the end of the period (in shares) | 4,235 | | 4,235 | |
Weighted-Average Grant-Date Fair Value | | | | |
Outstanding at beginning of the period (in dollars per share) | | | $ 9.79 | |
Granted (in dollars per share) | | | 4.05 | |
Forfeited (in dollars per share) | | | 8.91 | |
Vested (in dollars per share) | | | 9.67 | |
Outstanding at the end of the period (in dollars per share) | $ 6.94 | | 6.94 | |
Market/Service Vesting Restricted Stock Units | LTIP | | | | |
Weighted-Average Grant-Date Fair Value for awards | | | | |
Granted (in dollars per share) | | | $ 4.88 | |
Outstanding unvested awards activity | | | | |
Outstanding at the beginning of the period (in shares) | | | 6,578 | |
Granted (in shares) | | | 1,379 | |
Forfeited (in shares) | | | (70) | |
Vested (in shares) | | | (652) | |
Outstanding at the end of the period (in shares) | 7,235 | | 7,235 | |
Weighted-Average Grant-Date Fair Value | | | | |
Outstanding at beginning of the period (in dollars per share) | | | $ 14.24 | |
Granted (in dollars per share) | | | 4.88 | |
Forfeited (in dollars per share) | | | 14.49 | |
Vested (in dollars per share) | | | 15.81 | |
Outstanding at the end of the period (in dollars per share) | $ 12.31 | | 12.31 | |
Market/Service Vesting Restricted Stock Units | Minimum | LTIP | | | | |
Weighted-Average Grant-Date Fair Value for awards | | | | |
Granted (in dollars per share) | | | 4.83 | |
Weighted-Average Grant-Date Fair Value | | | | |
Granted (in dollars per share) | | | $ 4.83 | |
Significant assumptions used to calculate fair values | | | | |
Expected volatility (as a percent) | | | 44.00% | |
Risk-free interest rate (as a percent) | | | 0.50% | |
Market/Service Vesting Restricted Stock Units | Maximum | LTIP | | | | |
Weighted-Average Grant-Date Fair Value for awards | | | | |
Granted (in dollars per share) | | | $ 15.81 | |
Weighted-Average Grant-Date Fair Value | | | | |
Granted (in dollars per share) | | | $ 15.81 | |
Significant assumptions used to calculate fair values | | | | |
Expected volatility (as a percent) | | | 54.00% | |
Risk-free interest rate (as a percent) | | | 1.20% | |
Other disclosures | | | | |
Vesting percentage of the awards granted | | | 200.00% | |
Restricted Stock Awards and Restricted Stock Units | | | | |
Weighted-Average Grant-Date Fair Value | | | | |
Compensation expense not yet recognized | $ 41 | | $ 41 | |
Weighted average period over which compensation expense is to be recognized | | | 1 year 5 months 19 days | |