Stock-Based Compensation Stockholder's Equity (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Statement of Financial Position [Abstract]
Dividends, Common Stock, Cash	$ 71.1	$ 59.1
Stock Repurchased During Period, Shares	2,224,503
Stock Repurchased During Period, Value	$ 113.5
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	858,175
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	$ 35.5
Payments of Ordinary Dividends, Noncontrolling Interest	$ 24.9	$ 21.7