Income taxes (Details 4) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
U.S. Federal Net Operating Loss	$ 184.5
U.S. State Net Operating Loss	16.9
Foreign Net Operating Losses	54.1
U.S. Tax Credits	37.1
U.S. Alternative Minimum Tax Credit	0.3
Total operating loss and tax credit carry forwards	$ 292.9