Goodwill and Intangible Assets (Finite-Lived Intangible Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,839.1	$ 18.1
Accumulated Amortization	42.4	6.7
Net Carrying Amount	1,796.7	11.4
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,821.0	0.0
Accumulated Amortization	33.9	0.0
Net Carrying Amount	1,787.1	0.0
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8.6	8.6
Accumulated Amortization	6.9	6.4
Net Carrying Amount	1.7	2.2
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	9.5	9.5
Accumulated Amortization	1.6	0.3
Net Carrying Amount	$ 7.9	$ 9.2

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TrademarksAndTradeNamesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_OtherIntangibleAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: