Income taxes (Deferred Tax Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Reserves	$ 647	$ 610
Net operating loss carryforwards	83,289	85,282
R&D credit carryforwards	8,836	9,047
Depreciation/amortization deferred	15,862	16,978
Other	5,773	5,808
Net deferred taxes before valuation allowance	114,407	117,725
Less: Valuation allowance	(114,407)	(117,725)
Deferred tax assets	$ 0	$ 0