Leases - Operating lease liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Leases
Lease liability - short-term	$ 2,136		$ 2,169
Lease liability - long-term	8,041		$ 8,565
Operating lease liabilities	10,177
Operating lease cost	700	$ 700
Cash paid for operating leases	$ 700	$ 700
Remaining lease term	5 years 3 months 18 days
Discount rate	5.50%