Intangible assets Future intangible amortization schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Future intangible amortization schedule [Abstract]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 1,495
Finite-Lived Intangible Assets, Amortization Expense, Year Two	1,611
Finite-Lived Intangible Assets, Amortization Expense, Year Three	1,406
Finite-Lived Intangible Assets, Amortization Expense, Year Four	1,292
Finite-Lived Intangible Assets, Amortization Expense, Year Five	1,196
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	5,335
Finite-Lived Intangible Assets, Net	$ 12,335	$ 13,112