Legal Proceedings and Contingencies (Narrative) (Details) - IMTT $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Legal Proceedings and Contingencies [Line Items]
Minimum number of years for remediation activities	10 years
Maximum number of years for remediation activities	20 years
Minimum
Legal Proceedings and Contingencies [Line Items]
Estimated cost of remediation	$ 30
Maximum
Legal Proceedings and Contingencies [Line Items]
Estimated cost of remediation	$ 65

Estimate of reasonably possible loss exposure in excess of amount accrued for remediation, site restoration, postclosure, monitoring commitments, or other exit costs associated with the sale, disposal or abandonment of a particular property resulting from unanticipated contamination of the assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14435-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 5.Y.Q4)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14394-108349

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