Income Taxes (Uncertainties) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Jun. 30, 2018	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Beginning Balance	$ 436.0	$ 398.5
Increases related to acquisitions	284.0	0.0
Decreases related to settlements with tax authorities	0.0	(0.1)
Decreases related to statute of limitation expirations	(2.2)	(10.9)
Increases related to current year tax positions	3.5	30.3
Decreases related to prior year tax positions	(11.6)
Increases related to prior year tax positions		18.2
Unrecognized Tax Benefits, Ending Balance	$ 709.7	$ 436.0

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Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
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-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
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Amount of increase in unrecognized tax benefits resulting from acquisitions.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase 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 lapses of applicable statutes of limitations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 10
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