INTANGIBLES - Change in the Carrying Amount of Goodwill by Segment (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Goodwill [Roll Forward]
Balance beginning of period	$ 2,396.5
Additions	6,001.5
Foreign currency impact	(37.4)
Balance end of period	8,360.6
Freight Segment
Goodwill [Roll Forward]
Balance beginning of period	899.1
Additions	5,989.3
Foreign currency impact	(11.8)
Balance end of period	6,876.6
Transit Segment
Goodwill [Roll Forward]
Balance beginning of period	1,497.4
Additions	12.2
Foreign currency impact	(25.6)
Balance end of period	$ 1,484.0

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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-Topic 350
-SubTopic 20
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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