Equity Incentive Plan - Stock option (Details) - 2019 Equity Incentive Plan - USD ($)			3 Months Ended		12 Months Ended
		Feb. 26, 2020	Mar. 31, 2020		Dec. 31, 2019
Number of Shares
Balance at beginning of period (in shares)			3,742,144
Granted (in shares)		564,800	636,000	[1]
Exercised (in shares)			(86,872)
Cancelled (in shares)			(6,690)
Balance at end of period (in shares)			4,284,582		3,742,144
Vested and expected to vest at end of period (in shares)			4,284,582
Exercisable at end of period (in shares)			1,888,288
Vested at end of period (in shares)			1,374,666
Weighted-Average Exercise Price
Balance at beginning of period (in dollars per share)			$ 9.58
Granted (in dollars per share)	[1]		22.02
Exercised (in dollars per share)			4.82
Cancelled (in dollars per share)			11.43
Balance at end of period (in dollars per share)			11.52		$ 9.58
Vested and expected to vest at end of period (in dollars per share)			11.52
Exercisable at end of period (in dollars per share)			6.65
Vested at end of period (in dollars per share)			$ 7.21
Weighted-Average Remaining Contractual Life
Weighted-Average Remaining Contractual Life			8 years 7 months 6 days		8 years 7 months 6 days
Vested and expected to vest at end of period (in years)			8 years 7 months 6 days
Exercisable at end of period (in years)			7 years 9 months 18 days
Vested at end of period (in years)			7 years 8 months 12 days
Aggregate Intrinsic Value
Balance at beginning of period			$ 22,910
Balance at end of period			25,368		$ 22,910
Vested and expected to vest at end of period			25,368
Exercisable at end of period			18,813
Vested at end of period			$ 12,954

[1] The board of directors of the Company approved the grant of 564,800 stock options on February 26, 2020. As the Company prioritized other communications including COVID-19 related matters, the terms of the 564,800 stock options were not communicated until April 2020. As a result, the Company excluded these options from the computation of expense and option activity in the quarter ended March 31, 2020. These options will be included in the second Quarterly Report on Form 10-Q.