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Leases (Narrative) (Details)	12 Months Ended
	Dec. 31, 2020 contract superfundSites
Lessee, Lease, Description [Line Items]
Number of leases with restrictive covenants | superfundSites	102
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Lease renewal term	5 years
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	20 years
Lease renewal term	20 years
Land
Lessee, Lease, Description [Line Items]
Number of leases	232
Terminal
Lessee, Lease, Description [Line Items]
Number of leases	1

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- Definition

Lessee, Operating Lease, Number Of Contracts

+ References

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+ Details

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- Definition

Lessee, Operating Lease, Number Of Contracts With Restrictive Covenants

+ References

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- 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.

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- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

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- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

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