Fair Value Measurements - Schedule of Liabilities Measure on Recurring and Nonrecurring Basis (Details) - Level 2 - USD ($) $ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Carrying Value | 2% Convertible Senior Notes | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Financial instrument value | $ 59,058 | $ 171,698 |
| Carrying Value | 1.25% Convertible Senior Notes | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Financial instrument value | 269,904 | 0 |
| Estimated Fair Value | 2% Convertible Senior Notes | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Financial instrument value | 73,832 | 207,882 |
| Estimated Fair Value | 1.25% Convertible Senior Notes | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Financial instrument value | $ 339,163 | $ 0 |