Employee Retirement Plans and Postretirement Benefits Level 3 Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Prior year fair value of assets	$ 5,542.1	$ 5,217.3
Total gain or loss (realized/unrealized):
Foreign exchange translation (loss)/gain	113.9	150.5
Fair value of plan assets at end of year	5,958.4	5,542.1
Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Prior year fair value of assets	830.2	695.7
Total gain or loss (realized/unrealized):
Realized gain (loss)	2.1	15.3
Unrealized gain (loss) included in AOCI	11.0	(19.6)
Purchases, issuances, settlements	(12.7)	105.2
Foreign exchange translation (loss)/gain	25.7	33.6
Fair value of plan assets at end of year	$ 856.3	$ 830.2