Intangible Assets and Goodwill - Intangible Assets, by Major Class (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross amount	$ 8,343.8		$ 8,345.4
Accumulated amortization	(1,915.1)		(1,659.8)
Net amount	6,428.7		6,685.6
Projected Amortization Expense
2020	754.5
2021	946.1
2022	875.0
2023	681.1
2024	614.3
Impairment of intangible assets	$ 0.5	$ 2.0
Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life (in years)	1 year
Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life (in years)	15 years
Core and developed technology
Finite-Lived Intangible Assets [Line Items]
Gross amount	$ 7,411.9		7,413.0
Accumulated amortization	(1,331.7)		(1,112.9)
Net amount	6,080.2		6,300.1
Customer-related
Finite-Lived Intangible Assets [Line Items]
Gross amount	917.1		917.1
Accumulated amortization	(580.0)		(544.0)
Net amount	337.1		373.1
In-process research and development
Finite-Lived Intangible Assets [Line Items]
Gross amount	7.7		7.7
Accumulated amortization	0.0		0.0
Net amount	7.7		7.7
Distribution rights and other
Finite-Lived Intangible Assets [Line Items]
Gross amount	7.1		7.6
Accumulated amortization	(3.4)		(2.9)
Net amount	$ 3.7		$ 4.7