Leases - Balance sheet information (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Operating lease
Operating lease right-of-use assets	$ 12,097	$ 12,645
Operating lease liabilities, current	$ 2,964	$ 2,772
Operating Lease, Liability, Current, Statement of Financial Position	leaf:AccruedAndOtherLiabilitiesCurrent	leaf:AccruedAndOtherLiabilitiesCurrent
Operating lease liabilities, noncurrent	$ 10,112	$ 10,863
Total operating lease liabilities	$ 13,076	$ 13,635
Weighted average remaining lease term, Operating lease	4 years	4 years
Weighted average discount rate, Operating lease	9.00%	9.00%