Income Taxes Operating Loss Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
State net operating losses usable after limitations from Internal Revenue Code 382	$ 15.9
Deferred Tax Assets, Operating Loss Carryforwards, State and Local, Gross	2.5
Valuation allowance	27.2	$ 15.1
Foreign net operating loss carryforwards	12.4	$ 5.9
Investment Tax Credit	1.0
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance	2.2
Foreign Country [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance	12.1
Foreign operating losses available to carryforward	70.8
Foreign operating losses expiring between 2014 and 2016	67.6
Foreign operating losses to be carried forward indefinitely	$ 3.2