Equity Instruments and Share-Based Compensation - Stock Options (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Stock Options, Outstanding [Roll Forward]
Stock options outstanding, beginning balance (in shares) | shares	4,601
Granted (in shares) | shares	2,631
Exercised (in shares) | shares	0
Forfeited (in shares) | shares	(1,333)
Expired (in shares) | shares	(778)
Stock options outstanding, ending balance (in shares) | shares	5,121
Stock options exercisable (in shares) | shares	2,636
Stock Options, Outstanding, Weighted Average Exercise Price [Abstract]
Stock options outstanding, beginning balance (in usd per share) | $ / shares	$ 11.39
Granted (in usd per share) | $ / shares	2.24
Exercised (in usd per share) | $ / shares	0.00
Forfeited (in usd per share) | $ / shares	7.37
Expired (in usd per share) | $ / shares	12.91
Stock options outstanding, ending balance (in usd per share) | $ / shares	7.51
Stock options exercisable (in usd per share) | $ / shares	$ 11.63
Stock options outstanding, Weighted Average Remaining Contractual Life (in years)	7 years 5 months 5 days
Stock options exercisable, Weighted Average Remaining Contractual Life (in years)	5 years 8 months 23 days
Stock options outstanding, Aggregate Intrinsic Value | $	$ 12,119
Stock options exercisable, Aggregate Intrinsic Value | $	$ 572