Income Taxes - Components of Income Tax Provision (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current tax expense:
Federal		$ 62.3	$ 228.2	$ 79.6
State and local		4.6	9.8	14.3
Foreign		64.1	59.8	106.0
Total current expense		131.0	297.8	199.9
Deferred tax (benefit) expense:
Federal		(19.0)	56.8	130.1
State and local		4.0	(21.2)	5.3
Foreign		(39.4)	(25.9)	(4.8)
Total deferred tax (benefit) expense	$ (49.0)	(54.4)	9.7	130.6
Total income tax provision		$ 76.6	$ 307.5	$ 330.5