Earnings Per Share - Basic (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic earnings per share
Net income (loss)	$ 8,461	$ (19,103)	$ (27,300)	$ (19,769)
Less: cumulative preferred stock dividends	6,317	0	17,360	0
Net income (loss) attributable to common shareholders	$ 2,144	$ (19,103)	$ (44,660)	$ (19,769)
Weighted average common stock outstanding	78,353	75,974	78,290	69,149
Basic earnings (loss) per share, Net	$ 0.03	$ (0.25)	$ (0.57)	$ (0.29)