Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Basis Of Presentation [Line Items]
Recapitalization costs	$ 2,286	$ 1,423	$ 4,727	$ 5,799
Series B Preferred Stock
Basis Of Presentation [Line Items]
Cumulative exchangeable redeemable preferred stock dividend rate			10.75%		10.75%
12.5% Senior Secured Notes due 2017
Basis Of Presentation [Line Items]
Interest rate on Senior secured notes	12.50%		12.50%		12.50%
Senior secured notes, maturity date			Apr. 15, 2017