Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 763.4	$ 436.0	$ 398.5
Increases related to acquisitions	0.0	329.7	0.0
Decreases related to settlements with tax authorities	(1.2)	(8.3)	(0.1)
Decreases related to statute of limitation expirations	(30.9)	(16.2)	(10.9)
Increases related to current year tax positions	30.2	27.8	30.3
Decreases related to prior year tax positions	(4.2)	(5.6)
Increases related to prior year tax positions			18.2
Ending balance	$ 757.3	$ 763.4	$ 436.0

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from acquisitions.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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