Summary of significant accounting policies, Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Right-of-use asset	$ 2,855	$ 0
Lease liability	$ 2,104	0
Minimum [Member]
Leases [Abstract]
Remaining lease terms	1 year
Maximum [Member]
Leases [Abstract]
Remaining lease terms	8 years
Extension period for leases	5 years
Termination period for leases	1 year
ASC 842 [Member]
Leases [Abstract]
Right-of-use asset		3,700
Lease liability		$ 3,900