Development Derivative Liability - Narrative (Details)	1 Months Ended	3 Months Ended	9 Months Ended
	Jan. 31, 2020 USD ($)	Sep. 30, 2020 USD ($) tranche payment $ / shares shares	Sep. 30, 2020 USD ($) tranche payment $ / shares shares	Dec. 31, 2019 USD ($) shares
Derivative [Line Items]
Common stock, shares issued (in shares) | shares		29,389,288	29,389,288	28,796,371
Common stock, shares issued, value		$ 29,000	$ 29,000	$ 29,000
Derivative
Derivative [Line Items]
Initial payment, net of common stock warrants			2,100,000
Funding during the period			21,700,000
Change in fair value		$ 4,300,000	8,400,000
SFJ Agreement
Derivative [Line Items]
Potential milestones payment			$ 120,000,000.0
Cost of borrowing rate			16.00%
SFJ Pharmaceuticals
Derivative [Line Items]
Cost of borrowing rate			2.50%
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | SFJ Agreement
Derivative [Line Items]
Common stock, shares issued (in shares) | shares		2,200,000	2,200,000
Shares issued (in usd per share) | $ / shares		$ 6.50	$ 6.50
Common stock, shares issued term			10 years
Common stock, warrants exercisable term			1 year
Number of tranches | tranche		2	2
Common stock, shares issued, value		$ 7,900,000	$ 7,900,000
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | SFJ Agreement | Derivative
Derivative [Line Items]
Initial payment, net of common stock warrants			2,075,000
Funding during the period			21,714,000
Change in fair value			$ 8,435,000
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | SFJ Agreement | Tranche A
Derivative [Line Items]
Common stock, shares issued (in shares) | shares		1,100,000	1,100,000
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | SFJ Agreement | Tranche B
Derivative [Line Items]
Common stock, shares issued (in shares) | shares		1,100,000	1,100,000
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | bentracimab | SFJ Agreement
Derivative [Line Items]
Additional payment for license			$ 31,700,000
Additional payment received for license agreement			58,300,000
Initial payment received for license agreement			10,000,000.0
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | bentracimab | United States Food And Drug Administration | SFJ Agreement
Derivative [Line Items]
Additional payment for license			325,000,000.0
Initial payment for license			$ 5,000,000.0
Number of additional annual payments | payment		7	7
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | bentracimab | European Medicines Agency | SFJ Agreement
Derivative [Line Items]
Additional payment for license			$ 205,000,000.0
Initial payment for license			$ 5,000,000.0
Number of additional annual payments | payment		7	7
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | bentracimab | Pharmaceuticals And Medical Devices Agency Of Japan And National Medical Productions Administration Of China | SFJ Agreement
Derivative [Line Items]
Additional payment for license			$ 59,000,000.0
Initial payment for license			$ 1,000,000.0
Number of additional annual payments | payment		8	8
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | bentracimab | Maximum | SFJ Agreement
Derivative [Line Items]
Potential milestones payment receivable	$ 120,000,000.0		$ 30,000,000.0