Leases - Operating Leases (Details) $ in Thousands			1 Months Ended	6 Months Ended
	Jul. 17, 2020 USD ($)	Dec. 21, 2018 USD ($) ft²	Dec. 31, 2019 USD ($)	Jun. 30, 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 | $	$ 14	$ 13