Income Taxes Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, beginning balance	$ 15.6	$ 0.0
Additions for tax positions taken during the current period	0.0	15.6
Unrecognized tax benefits, ending balance	$ 15.6	$ 15.6