Income taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Income Taxes Narrative Details
Provision for income taxes	$ 0.0	$ 0.0
Operating Loss Carryforwards	$ 398.1
Operating loss carryforwards, expiration date	Dec. 31, 2019
Annual limit on operating loss carryforwards	<p style="font: 10pt Times New Roman, Times, Serif; margin-right: 0; margin-left: 0">In certain circumstances, as specified in the Internal Revenue Code, a 50% or more ownership change by certain combinations of our shareholders during any three year period would result in limitations on our ability to use a portion of our net operating loss carryforwards.</p> <p style="font: 10pt Times New Roman, Times, Serif; margin-right: 0; margin-left: 0"> </p> <p style="font: 10pt Times New Roman, Times, Serif; margin-right: 0; margin-left: 0"></p> <p style="font: 10pt Times New Roman, Times, Serif; margin-right: 0; margin-left: 0"> </p>
Accrued penalties and interest	$ 0.0
Unrecognized tax benefits	$ 0.0
Tax years open for examination	1998

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

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Tax year that remains open to examination under enacted tax laws, in CCYY format.

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Expiration date of each operating loss carryforward included in operating loss carryforward, in CCYY-MM-DD format.

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A description of the limitations on the use of all operating loss carryforwards available to reduce future taxable income.

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Amount of unrecognized tax benefits.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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