Leases - Operating Leases (Details) $ in Thousands		1 Months Ended	3 Months Ended
	Dec. 21, 2018 USD ($) ft²	Dec. 31, 2019 USD ($)	Mar. 31, 2020	Nov. 07, 2018 ft²	Jun. 26, 2018 ft²
Maximum
Operating leases
Remaining lease terms			2 years
Lexington office
Operating leases
Area of leased space after expansion | ft²				55,924	27,244
Monthly base rent payment | $		$ 138
San Diego office
Operating leases
Area of leased space after expansion | ft²	4,400
Monthly base rent payment | $	$ 13