Preferred Stock - Additional Information (Details) $ in Millions |
3 Months Ended | |||
---|---|---|---|---|
Mar. 31, 2018
USD ($)
shares
|
Mar. 31, 2017
USD ($)
|
Mar. 31, 2016
Tranche
shares
|
Dec. 31, 2017
USD ($)
shares
|
|
Class Of Stock [Line Items] | ||||
Number of tranches sold to investors | Tranche | 2 | |||
Preferred Series A dividends payable | $ | $ 22.9 | $ 22.9 | ||
Preferred stock dividend paid | $ | $ 22.9 | |||
Accrued preferred dividends payable date | May 14, 2018 | |||
Deemed dividends on Series A Preferred Stock | $ | $ 7.0 | $ 6.1 | ||
Series A Preferred Stock [Member] | ||||
Class Of Stock [Line Items] | ||||
Preferred Stock, Shares Issued | 965,100 | 965,100 | ||
Private Placement [Member] | Series A Warrants [Member] | ||||
Class Of Stock [Line Items] | ||||
Warrants exercisable | 13,550,004 | |||
Private Placement [Member] | Series B Warrants [Member] | ||||
Class Of Stock [Line Items] | ||||
Warrants exercisable | 6,533,727 | |||
Private Placement [Member] | Series A Preferred Stock [Member] | ||||
Class Of Stock [Line Items] | ||||
Preferred Stock, Shares Issued | 965,100 |