Changes in Operations United States P&W (Details) - Providence and Worcester Railroad [Member] - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
Nov. 01, 2016	Dec. 31, 2017
Business Acquisition, Effective Date of Acquisition	Nov. 01, 2016
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
Business Acquisition, Share Price	$ 25.00
Cash consideration	$ 126.2
Business Combination, Integration Related Costs		$ 3.1
Labor and Benefits [Member]
Business Combination, Integration Related Costs		2.7
Other Expense [Member]
Business Combination, Integration Related Costs		$ 0.4

Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

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Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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