Income taxes (Loss carryforwards) (Details) $ in Thousands	Dec. 31, 2016 USD ($)
United States
Operating and Capital Loss Carryforwards [Line Items]
Loss Carryforwards	$ 11,195
Loss Carryforwards, Tax Effect	3,918
Switzerland
Operating and Capital Loss Carryforwards [Line Items]
Loss Carryforwards	157,512
Loss Carryforwards, Tax Effect	33,078
Luxembourg
Operating and Capital Loss Carryforwards [Line Items]
Loss Carryforwards	300,121
Loss Carryforwards, Tax Effect	78,310
Singapore
Operating and Capital Loss Carryforwards [Line Items]
Loss Carryforwards	11,090
Loss Carryforwards, Tax Effect	$ 1,109