Share-Based Payments - 2017 Share Incentive Plan (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) tranche $ / shares shares
Additional disclosures
Share-based compensation expense | $	$ 5,219	$ 9,748	$ 5,154
2017 Share Incentive Plan
Options
Outstanding at beginning of year (in shares) | shares	442,266	239,842	29,410
Granted (in shares) | shares	129,050	246,330	219,922
Forfeited (in shares) | shares	(128,472)	(43,906)	(9,490)
Outstanding at end of year (in shares) | shares	442,844	442,266	239,842
Vested and exercisable at end of year (in shares) | shares	228,731	112,028	11,928
Weighted average exercise price in $ per share
Outstanding balance at beginning of year (in dollars per share)	$ 35.48	$ 54.14	$ 69.17
Granted (in dollars per share)	13.50	19.51	52.71
Forfeited (in dollars per share)	29.39	47.87	67.52
Outstanding balance at end of year (in dollars per share)	30.89	35.48	54.14
Vested and exercisable balance at end of year (in dollars per share)	$ 39.02	$ 55.33	$ 68.77
Additional disclosures
Weighted average remaining contractual life	8 years 2 months 12 days
2017 Share Incentive Plan | $1.46 per share to $8.35 per share
Additional disclosures
Exercise price minimum range	$ 13.50
Exercise price maximum range	$ 81.90
2017 Share Incentive Plan | Stock Options
Fair Value Assumptions
Expected term of options (in years)	6 years 1 month 6 days	6 years	6 years 1 month 6 days
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Additional disclosures
Share-based compensation expense | $	$ 2,000	$ 2,600	$ 1,800
Weighted-average grant date fair value (in dollars per share)	$ 7.97	$ 11.38	$ 30.64
Total unrecognized compensation related to unvested options | $	$ 2,600
Recognition period	10 months 24 days
2017 Share Incentive Plan | Stock Options | Minimum
Fair Value Assumptions
Expected volatility (as a percent)	63.80%	61.40%	59.80%
Risk-free interest rate (as a percent)	0.80%	1.90%	2.60%
2017 Share Incentive Plan | Stock Options | Maximum
Fair Value Assumptions
Expected volatility (as a percent)	64.00%	63.10%	61.40%
Risk-free interest rate (as a percent)	1.50%	2.60%	3.00%
2017 Share Incentive Plan | Restricted Stock Units ("RSUs")
Additional disclosures
Share-based compensation expense | $	$ 1,400	$ 2,700	$ 200
Recognition period	1 year 1 month 6 days
Restricted Stock Units
Number of shares outstanding | shares	151,269	90,169	122,210
weighted average fair value per share
Weighted average fair value at the beginning	$ 27.37	$ 33.10
Granted	13.50	19.00
Forfeited	17.23	27.87
Weighted average fair value at the end	$ 14.56	$ 27.37	$ 33.10
Additional Disclosures
Percentage that vests during the period	25.00%
2017 Share Incentive Plan | Restricted Stock Units ("RSUs") | XENLETA
Additional Disclosures
Number of vesting periods | tranche			3
Vesting period			6 months
2017 Share Incentive Plan | Restricted Stock Units ("RSUs") | Immediate vesting upon regulatory approval | XENLETA
Additional Disclosures
Percentage that vests during the period			50.00%
2017 Share Incentive Plan | Restricted Stock Units ("RSUs") | Immediate vesting upon regulatory approval | CONTEPO
Additional Disclosures
Percentage that vests during the period			50.00%
2017 Share Incentive Plan | Restricted Stock Units ("RSUs") | Vesting upon the one-year-anniversary of FDA approval | XENLETA
Additional Disclosures
Percentage that vests during the period			50.00%
2017 Share Incentive Plan | Restricted Stock Units ("RSUs") | Vesting upon the one-year-anniversary of FDA approval | CONTEPO
Additional Disclosures
Percentage that vests during the period			50.00%