Stock-Based Compensation - Options Activity, Unrecognized Costs, Valuation (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Options
Balance (in shares)	1,637,399	542,550
Granted as an inducement grant (in shares)	150,000
Exercised (in shares)		(15,957)
Forfeited (in shares)	(113,906)
Balance (in shares)	1,808,493	1,637,399
Weighted Average Grant Date Fair Value
Balance (in dollars per share)	$ 6.47	$ 0.84
Granted as an inducement grant (in dollars per share)	6.95
Forfeited (in dollars per share)	8.12
Exercised (in dollars per share)		0.84
Balance (in dollars per share)	6.36	6.47
Weighted average exercise price per share
Balance (in dollars per shares)	10.49	3.98
Granted as an inducement grant (in dollars per share)	10.23
Forfeited (in dollars per share)	12.67
Exercised (in dollars per share)		3.98
Balance (in dollars per shares)	$ 10.22	$ 10.49
Additional disclosures
Expected stock based compensation expense	$ 7.3
Recognition period for compensation costs	2 years 6 months 22 days
Options exercisable (in shares)	641,375
Options exercisable grant date fair value (in dollars per share)	$ 5.18
Stock options expected to vest (in shares)	1,154,618
Stock options weighted average contractual life	8 years 6 months
Stock options aggregate intrinsic value	$ 9.7
Assumptions and Methodology
Expected volatility (as a percent)	77.00%
Minimum expected volatility (as a percent)		76.00%
Maximum expected volatility (as a percent)		77.00%
Minimum risk-free interest rate (as a percent)	1.40%	1.70%
Maximum risk-free interest rate (as a percent)	2.20%	2.00%
Dividend yield (as a percent)	0.00%	0.00%
2014 Plan
Options
Granted (in shares)	135,000	1,110,806
Weighted Average Grant Date Fair Value
Granted (in dollars per share)	$ 5.96	$ 9.13
Weighted average exercise price per share
Granted (in dollars per shares)	$ 8.99	$ 13.58
Minimum
Assumptions and Methodology
Expected term (in years)	5 years 6 months	5 years 9 months
Maximum
Assumptions and Methodology
Expected term (in years)	6 years 3 months	6 years 3 months