Intangible Assets Intangible Assets Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets Abstract
Amortization of intangible assets	$ 139.3	$ 132.0	$ 132.0
Future estimated amortization expense, 2015	139.0
Future estimated amortization expense, 2016	137.0
Future estimated amortization expense, 2017	137.0
Future estimated amortization expense, 2018	137.0
Future estimated amortization expense, 2019	$ 135.0