Income Taxes - Narrative (Details) $ in Millions, ₩ in Billions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 KRW (₩)	Dec. 31, 2021 USD ($)	Dec. 31, 2017	Feb. 29, 2012 KRW (₩)	Feb. 29, 2012 USD ($)
Tax Credit Carryforward [Line Items]
Income taxes paid	$ 137.8
Deferred tax liabilities, temporary differences, purchase accounting, foreign subsidiaries	1,500.0
Total deferred charges and prepaid taxes	56.6					$ 39.6
Deferred tax asset, net						100.0
Valuation allowance	2,003.3			$ 85.0		1,961.3
Unrecognized tax benefit	134.0		$ 68.8			87.5
Net interest expense	0.7	$ 2.7	1.0
Unrecognized tax benefits, interest on income taxes accrued	25.2					24.8
Decrease in unrecognized tax benefits is reasonably possible	500.0
Samsung Bioepis
Tax Credit Carryforward [Line Items]
Investment in Samsung Bioepis					₩ 713.3	599.9		₩ 49.5	$ 45.0
2017 Tax Act
Tax Credit Carryforward [Line Items]
Transition toll tax liabilities	558.0					$ 633.0
Domestic Country
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	24.8
Foreign Tax Authority
Tax Credit Carryforward [Line Items]
Increase in unrecognized tax benefit	450.0	455.0
General Business | Domestic Country
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	8.1
Operating loss carryforward, subject to expiration	15,500.0
General Business | Foreign Tax Authority
Tax Credit Carryforward [Line Items]
Operating loss carryforward, subject to expiration	15,400.0
Research | State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	132.7
Earnings in the form of cash and cash equivalents | 2017 Tax Act
Tax Credit Carryforward [Line Items]
Transition toll tax repatriation tax rate							15.50%
Other Foreign Earnings | 2017 Tax Act
Tax Credit Carryforward [Line Items]
Transition toll tax repatriation tax rate							8.00%
Minimum
Tax Credit Carryforward [Line Items]
Residual U.S. tax liability on reversal of deferred tax liabilities on foreign subsidiaries purchase accounting	300.0
Maximum
Tax Credit Carryforward [Line Items]
Residual U.S. tax liability on reversal of deferred tax liabilities on foreign subsidiaries purchase accounting	400.0
TECFIDERA
Tax Credit Carryforward [Line Items]
Deferred tax assets, value, reduction in value			1,700.0
Deferred tax liabilities, value, reduction in value			1,600.0
Income tax expense, reduction in deferred tax assets and liabilities, net			$ 90.3
Deferred tax assets, increase in value	17.4	108.5
Deferred tax liability, increase in value	$ 16.7	$ 103.9