Income Taxes - Summary of Unrecognized Tax Benefit Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits, beginning of year	$ 32.2	$ 46.1	$ 23.8
Increases in prior year tax positions	35.7	11.4	27.1
Decreases in prior year tax positions	(2.6)	(1.8)	(1.2)
Increases for current year tax positions	4.7	5.9	6.6
Expiration of statute of limitations and audit settlements	(4.1)	(29.4)	(10.2)
Gross unrecognized tax benefits, end of year	65.9	32.2	46.1
Potential interest and penalties	3.6	2.0	20.4
Balance, end of year	$ 69.5	$ 34.2	$ 66.5