Comprehensive Earnings (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision	$ 596.3	$ 9.9
Net unrealized gain on marketable securities, net of tax	0.2		$ 1.2
Net unrecognized losses and prior service cost related to defined benefit plans, net of tax	26.3		(26.1)
Foreign currency translation adjustment	(1,182.7)		(461.5)
Accumulated other comprehensive loss	(1,385.6)		(858.0)
Other comprehensive loss, before tax	(490.6)	(667.1)
Net unrealized (loss) gain on marketable securities	(0.9)	0.2
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	(0.8)	1.6
Sales Revenue, Goods, Net	4,400.1	2,588.2
Interest expense	169.0	119.9
Cash Flow Hedging
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrecognized gain (loss) on derivatives	3.3
Net Investment Hedging
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulate Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Net Investment Hedges, Effect Net of Taxx	(161.3)		(353.6)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision		(10.8)
Accumulated other comprehensive loss		(2,453.5)		$ (1,797.2)
Other comprehensive earnings (loss) before reclassifications, before tax	(485.8)	(668.3)
Gains and Losses on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision		(12.9)
Net unrecognized loss on derivatives in cash flow hedging relationships, net of tax		(70.1)		(31.6)
Other comprehensive earnings (loss) before reclassifications, before tax		(52.4)
Gains and Losses on Derivatives | Cash Flow Hedging
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision	0.8
Net unrecognized loss on derivatives in cash flow hedging relationships, net of tax	(15.5)		$ (18.0)
Other comprehensive earnings (loss) before reclassifications, before tax	8.3
Gains and Losses on Derivatives | Net Investment Hedging
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision	35.1	2.1
Net unrecognized loss on derivatives in cash flow hedging relationships, net of tax		(34.1)		(74.3)
Other comprehensive earnings (loss) before reclassifications, before tax		42.3
Gains and Losses on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision		0.0
Net unrealized gain on marketable securities, net of tax		0.8		0.6
Other comprehensive earnings (loss) before reclassifications, before tax		0.2
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision		0.0
Net unrecognized losses and prior service cost related to defined benefit plans, net of tax		(19.0)		(17.4)
Other comprehensive earnings (loss) before reclassifications, before tax	0.6	(1.8)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision		0.0
Foreign currency translation adjustment		(2,331.1)		$ (1,674.5)
Other comprehensive earnings (loss) before reclassifications, before tax	(721.2)
Reclassification out of Accumulated Other Comprehensive Income [Member] | AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision	37.0
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	0.1
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	(0.3)	(0.2)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains and Losses on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrecognized gain (loss) on derivatives		(51.4)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains and Losses on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision	0.1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision	1.0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax		1.6
Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (benefit) provision	0.0
Other comprehensive loss, before tax		(656.6)
Mylan N.V. | Net Investment Hedging
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrecognized gain (loss) on derivatives	227.4	42.3
Foreign currency forward contracts | Gains and Losses on Derivatives | Cash Flow Hedging
Accumulated Other Comprehensive Income (Loss) [Line Items]
Sales Revenue, Goods, Net	(6.1)
Foreign currency forward contracts | Reclassification out of Accumulated Other Comprehensive Income [Member] | AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Sales Revenue, Goods, Net	(6.1)	(0.1)
Foreign currency forward contracts | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains and Losses on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Sales Revenue, Goods, Net	(6.1)	(0.1)
Interest rate swaps | Gains and Losses on Derivatives | Cash Flow Hedging
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest expense	1.1
Interest rate swaps | Reclassification out of Accumulated Other Comprehensive Income [Member] | AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest expense	1.1	1.1
Interest rate swaps | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains and Losses on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest expense	1.1	1.1
Pension and other postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	0.1	0.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	(0.3)	$ (0.2)
Pension and other postretirement benefits | Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	$ 0.1