Income Taxes - Summary of Unrecognized Tax Benefit Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits, beginning of year	$ 65.9	$ 32.2	$ 46.1
Increases in prior year tax positions	1.4	35.7	11.4
Decreases in prior year tax positions	(4.1)	(2.6)	(1.8)
Increases for current year tax positions	3.2	4.7	5.9
Expiration of statute of limitations and audit settlements	(5.5)	(4.1)	(29.4)
Gross unrecognized tax benefits, end of year	60.9	65.9	32.2
Potential interest and penalties	3.6	3.6	2.0
Balance, end of year	$ 64.5	$ 69.5	$ 34.2