Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended				24 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Income Tax Contingency [Line Items]
Accrued liabilities for interest and penalties		$ 0.3	$ 0.2
Total gross unrecognized tax benefits		10.4	5.0	$ 3.9		$ 3.9
Estimated increase (decrease) in the liability for unrecognized tax benefits		(0.3)
Tax benefit from impact of tax law changes enacted	$ (1.0)	0.5	0.3	2.5
Tax benefit from stock-based compensation		$ 20.8	$ 10.3	$ 14.3
U.S. federal corporate tax rate		21.00%	21.00%	21.00%	35.00%
Transition toll tax				$ (7.5)	$ 27.9	$ 20.4
Measurement period adjustment, Tax Cuts and Jobs Act of 2017				$ 4.0
Net impact to the 2018 effective tax rate, Tax Cuts and Jobs Act of 2017				0.0145
Operating loss carryforwards, state and local		$ 14.0
Operating loss carryforwards, foreign		7.4
Undistributed earnings of foreign subsidiaries		345.6
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Operating loss carryforwards		204.1
Foreign Tax Authority
Income Tax Contingency [Line Items]
Operating loss carryforwards		56.7
Operating loss carryforwards, not subject to expiration		54.1
Year 2021 | State and Local Jurisdiction
Income Tax Contingency [Line Items]
Operating loss carryforwards		25.7
Year After 2021 | State and Local Jurisdiction
Income Tax Contingency [Line Items]
Operating loss carryforwards		178.4
Research Tax Credit Carryforward | State and Local Jurisdiction
Income Tax Contingency [Line Items]
Tax credit carryforward		$ 0.9