Income taxes (Credit Carryforwards Narrative) (Details) (USD $)
In Millions, unless otherwise specified

12 Months Ended

Dec. 31, 2014

Tax credit carryforwards, expiration dates

The net operating loss carry-forwards and research and development credits available to offset future taxable income, if any, will expire in varying amounts from 2018 to 2034 if not previously utilized.

R&D Tax Credit

Tax Credit Carryforward, Description

Research and development credits available to offset future taxable income.

Tax Credit Carryforward, Amount

6.5

Tax Credit Carryforward, Expiration Date

Dec. 31, 2018

Tax credit carryforwards, expiration dates

The net operating loss carry-forwards and research and development credits available to offset future taxable income, if any, will expire in varying amounts from 2018 to 2034 if not previously utilized.

Capital Loss Carryforward

Tax Credit Carryforward, Description

Capital loss carry-forwards that are scheduled to expire between 2015 and 2017.

Tax Credit Carryforward, Amount

1.2

Tax Credit Carryforward, Expiration Date

Dec. 31, 2015

Tax credit carryforwards, expiration dates

In addition to the tax benefits above, we have $1.2 million of capital loss carry-forwards that are scheduled to expire between 2015 and 2017.