Stock Based Compensation - Alize Acquisition (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2020 $ / shares shares	Sep. 30, 2020 $ / shares shares	Dec. 19, 2017 € / shares shares
BSPCE warrants
Class of Warrant or Right [Line Items]
BSPCE warrants exercised (in shares)	0	910
BSA and BSPCE warrants
Class of Warrant or Right [Line Items]
BSA and BSPCE warrants forfeited (in shares)	0	2,586
Alize | BSA and BSPCE warrants
Class of Warrant or Right [Line Items]
Weighted average exercise prices (in dollars per share) | $ / shares	$ 7.49	$ 7.49
Number of shares issued upon the exercise of the warrants (in shares)	12,307	12,307
Number of shares issuable upon the exercise of the warrants (in shares)	48,265	48,265
Alize | BSA and BSPCE warrants | BSA warrants
Class of Warrant or Right [Line Items]
Common stock warrants outstanding (in shares)			6,219
Weighted average exercise prices (in dollars per share) | € / shares			€ 80.06
Alize | BSA and BSPCE warrants | BSPCE warrants
Class of Warrant or Right [Line Items]
Common stock warrants outstanding (in shares)			5,360
Weighted average exercise prices (in dollars per share) | € / shares			€ 83.40