Debt - Convertible Notes - Narrative (Details) |
May. 31, 2014
USD ($)
$ / shares
|
Jun. 30, 2015
USD ($)
|
Dec. 31, 2014
USD ($)
|
|---|---|---|---|
| Debt Instrument [Line Items] | |||
| Deferred financing costs | $ 42,870,000 | $ 46,332,000 | |
| Convertible Senior Notes | |||
| Debt Instrument [Line Items] | |||
| Conversion rate | 0.0763636 | ||
| Conversion price | $ / shares | $ 13.10 | ||
| Premium above public offering price | 22.50% | ||
| Value of the embedded conversion premium, included in net debt (discount) | $ 56,700,000 | 47,200,000 | 51,500,000 |
| Deferred financing costs | 19,600,000 | ||
| Unamortized deferred financing costs | $ 16,200,000 | $ 17,800,000 | |
| Convertible Senior Notes | Convertible Senior Notes Due 2019 | |||
| Debt Instrument [Line Items] | |||
| Aggregate principal amount of debt | $ 402,500,000.0 | ||
| Stated Rates | 2.875% | ||
| Convertible Senior Notes | Convertible Senior Notes Due 2021 | |||
| Debt Instrument [Line Items] | |||
| Aggregate principal amount of debt | $ 345,000,000.0 | ||
| Stated Rates | 3.75% |