Share-Based Compensation - Nonrecourse Promissory Notes with related parties (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Feb. 28, 2019	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares that becomes outstanding		406,894
Interim Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares early exercised	688,875
Interim Chief Operating Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares early exercised	309,994
Promissory Note With Related Parties
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Interest rate of notes receivable	2.91%
Promissory Note With Related Parties | Interim Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Notes receivable in exchange of stock options exercised	$ 0.2
Promissory Note With Related Parties | Interim Chief Operating Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Notes receivable in exchange of stock options exercised	$ 0.8