Income Taxes - Operating Loss and Tax Credit Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Charitable contribution carryover (CCCs)	$ 38.4	$ 23.7
US State
Operating Loss Carryforwards [Line Items]
Net operating losses	131.2	128.8
Tax credit carryforwards	4.0	5.5
US Federal
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	12.2	7.8
Foreign
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 34.1	$ 38.0