Income Taxes - Operating loss carry forwards (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Net operating loss carry forwards
Net operating loss carry forward	$ 6.5	$ 7.3
Foreign
Net operating loss carry forwards
Net operating loss carry forward	26.1
Net operating loss carryforward, not subject to expiration	26.1
Austria
Net operating loss carry forwards
Net operating loss carry forward	26.1
U.S.
Net operating loss carry forwards
Net operating loss carry forward	$ 0.3