Stock-Based Compensation Stock-based Compensation (Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock or Unit Option Plan Expense	$ 0.0	$ 0.7	$ 1.1
Restricted Stock or Unit Expense	29.2	29.2	36.1
Stock-based compensation expense	29.2	29.9	37.2
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	12.9	11.5	13.3
Allocated Share-based Compensation Expense, Net of Tax	$ 16.3	$ 18.4	$ 23.9