Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Name:	us-gaap_GainLossOnSaleOfPropertyPlantEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Sales of Vessels (Details) $ in Thousands	3 Months Ended		9 Months Ended
Sales of Vessels (Details) $ in Thousands	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($) vessel
Property, Plant and Equipment [Line Items]
Gain on sale of vessel (note 16) \| $	$ 0	$ 0	$ 0	$ 170
Voyage Charters - Full Service Lightering [Member]
Property, Plant and Equipment [Line Items]
Number Of Vessels Sold \| vessel				1