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Property, Plant and Equipment (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Mar. 31, 2019
Property, Plant and Equipment [Line Items] |  |
Acquisitions of freight management companies |  | $ 21
Contingent consideration |  | $ 8
Corporate Services [Member] | Minimum [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Property, plant and equipment, useful life | 5 years |
Corporate Services [Member] | Maximum [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Property, plant and equipment, useful life | 30 years |
Sheboygan Falls Energy Facility [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Property, plant and equipment, useful life | 35 years |
Customer Billing And Information System [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Property, plant and equipment, useful life | 12 years |
Software [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Property, plant and equipment, useful life | 5 years |

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- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
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