Income Taxes - Components of Income Tax (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of income before provision for income taxes and noncontrolling interest
Domestic									$ 204.2	$ 296.2	$ 160.6
Foreign									61.0	118.2	372.1
Income before income taxes	$ 39.2	$ 111.6	$ 86.1	$ 28.3	$ 174.0	$ 118.1	$ 77.8	$ 44.5	265.2	414.4	532.7
Current provision (benefit):
Federal									73.4	6.2	(126.1)
States									20.3	14.4	9.0
Foreign									(21.6)	48.5	38.9
Total current provision (benefit)									72.1	69.1	(78.2)
Deferred (benefit) provision:
Federal									(58.7)	0.8	36.6
States									(6.6)	2.8	2.2
Foreign									0.6	(3.3)	5.2
Total deferred (benefit) provision									(64.7)	0.3	44.0
Total provision (benefit) for income taxes									7.4	69.4	(34.2)
Income tax reconciliation
Expected provision at statutory rate									55.7	87.0	111.9
State taxes, net of federal benefit									8.7	9.4	7.4
Foreign income at different tax rates									(5.9)	1.8	(12.8)
R&D tax credits									(16.4)	(18.8)	(22.1)
Share-based compensation									9.0	3.8	4.7
Non-deductible compensation									3.5	3.3	1.9
Temporary differences not currently benefited									(0.9)	12.9	0.0
Recognition of previously unrecognized tax benefits									(63.7)	(25.4)	0.0
Cost sharing adjustment- Altera									20.1	0.0	0.0
Lapses in federal statutes of limitations									0.0	(7.5)	(67.6)
Tax accounting method changes									0.0	0.0	(65.4)
Impact of the U.S. Tax Cuts and Jobs Act									0.0	0.0	2.8
Other									(2.7)	2.9	5.0
Total provision (benefit) for income taxes									$ 7.4	$ 69.4	$ (34.2)