Balance Sheet Account Detail - Facility and Equipment Under Lease (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Facility and equipment under lease	$ 3,467	$ 3,806
Office and research facilities
Lessee, Lease, Description [Line Items]
Facility and equipment under lease	3,077	3,391
Office equipment
Lessee, Lease, Description [Line Items]
Facility and equipment under lease	$ 390	$ 415