Income Taxes, Valuation allowance and tax carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income taxes
Valuation allowance, related to the foreign net operating loss carryforwards and U.S. state tax credits	$ 35.2	$ 34.7
Foreign
Income taxes
Loss carryforwards	146.4
Operating loss carryforwards to expire or be refunded	95.8
Tax credit carryforwards	3.8
Tax credit carryforwards to expire or be refunded	3.8
U.S. Federal
Income taxes
Loss carryforwards	0.7
Operating loss carryforwards to expire or be refunded	0.7
U.S. State
Income taxes
Loss carryforwards	56.0
Operating loss carryforwards to expire or be refunded	56.0
Tax credit carryforwards	13.7
Tax credit carryforwards to expire or be refunded	$ 7.9