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Accounting Policies Property, Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2017
Minimum | Building and building improvements
Estimated useful life (years)	15 years
Minimum | Pipelines, tanks and terminals
Estimated useful life (years)	15 years
Minimum | Asset retirement obligation assets
Estimated useful life (years)	15 years
Minimum | Other equipment
Estimated useful life (years)	3 years
Maximum | Building and building improvements
Estimated useful life (years)	40 years
Maximum | Pipelines, tanks and terminals
Estimated useful life (years)	40 years
Maximum | Asset retirement obligation assets
Estimated useful life (years)	50 years
Maximum | Other equipment
Estimated useful life (years)	15 years

X

- 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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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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