Employee Retirement Plans - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0.2	$ 0.0	$ 0.5	$ 0.2
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	1.1		1.1
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(2,160.4)	$ (2,529.6)	(2,160.4)	$ (2,529.6)	$ (2,466.1)	$ (2,378.9)	$ (2,565.1)	$ (2,562.0)
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	15.0		15.0
Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	155.0		155.0
Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 185.0		$ 185.0
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Defined Benefit Plan Disclosure [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest						(170.1)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Defined Benefit Plan Disclosure [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest						$ (131.2)