Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
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
Impact of the U.S. Tax Cuts and Jobs Act	0.0	0.0	2.8
Valuation allowance	261.5	249.4
Increase (decrease) in DTA valuation allowance	12.1	15.7
Undistributed earnings of foreign subsidiaries		60.2
Additional income tax expense related to undistributed earnings	12.0
Unrecognized tax benefits	116.0	151.3	178.1	$ 264.5
Unrecognized tax benefits that would impact effective tax rate	92.8
Unrecognized tax benefits, penalties and interest	20.7	2.8	5.2
Reductions in unrecognized tax benefits	52.0	3.3	33.8
Minimum
Income Tax Contingency [Line Items]
Reductions in unrecognized tax benefits	10.6
Other long-term liabilities
Income Tax Contingency [Line Items]
Interest and penalties accrued related to unrecognized tax benefits	5.3	$ 29.9	$ 33.8
Federal
Income Tax Contingency [Line Items]
Net operating loss carry-forwards	172.9
Tax credit carry-forwards	6.3
Release of unrecognized tax benefits	9.0
Foreign Tax Authority | Ministry of Finance, India
Income Tax Contingency [Line Items]
Unrecognized tax benefits, penalties and interest	(18.4)
Release of unrecognized tax benefits	58.8
California Deferred Tax Assets
Income Tax Contingency [Line Items]
Valuation allowance	225.2
California Deferred Tax Assets | State and Local Jurisdiction
Income Tax Contingency [Line Items]
Net operating loss carry-forwards	134.0
Tax credit carry-forwards	266.0
Massachusetts Deferred Tax Assets
Income Tax Contingency [Line Items]
Valuation allowance	28.6
Canadian Deferred Tax Assets
Income Tax Contingency [Line Items]
Valuation allowance	3.4
Capital Loss Carryforward
Income Tax Contingency [Line Items]
Valuation allowance	$ 1.6