Derivative Instruments and Hedging Activities - Assumptions Used (Details) |
Sep. 30, 2018
year
$ / shares
|
Dec. 15, 2017
year
$ / shares
|
|---|---|---|
| Expected volatility | ||
| Derivative [Line Items] | ||
| Warrants, measurement input | 0.5014 | 0.5438 |
| Expected volatility | As Previously Reported | ||
| Derivative [Line Items] | ||
| Warrants, measurement input | 0.5457 | |
| Risk-free interest rates | ||
| Derivative [Line Items] | ||
| Warrants, measurement input | 0.0290 | 0.0220 |
| Risk-free interest rates | As Previously Reported | ||
| Derivative [Line Items] | ||
| Warrants, measurement input | 0.0220 | |
| Expected remaining life (in years) | ||
| Derivative [Line Items] | ||
| Warrants, measurement input | year | 4.21 | 5.00 |
| Expected remaining life (in years) | As Previously Reported | ||
| Derivative [Line Items] | ||
| Warrants, measurement input | year | 5.00 | |
| Warrants | ||
| Derivative [Line Items] | ||
| Price per share of common stock (in usd per share) | $ / shares | $ 22.14 | $ 15.16 |
| Warrants | As Previously Reported | ||
| Derivative [Line Items] | ||
| Price per share of common stock (in usd per share) | $ / shares | $ 14.93 |