PROPERTY, PLANT AND EQUIPMENT

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

The following table includes property, plant and equipment of our consolidated entities:


	2020			2019
December 31 (millions of dollars)	Cost	Accumulated Depreciation	Net Book Value	Cost	Accumulated Depreciation	Net Book Value
Pipeline	1,910	(982)	928	1,907	(929)	978
Compression	730	(210)	520	584	(202)	382
Metering and other (a)	208	(58)	150	180	(56)	124
Construction in progress	149	—	149	44	—	44
	2,997	(1,250)	1,747	2,715	(1,187)	1,528

(a)Includes the commercial system purchase described under Note 17 related to our consolidated entities amounting to $26 million and does not include our portion of the capital expenditure related to our equity investment in Great Lakes, amounting to $12 million.

2018 Impairment of Bison’s long-lived assets

At December 31, 2018, the Partnership performed an impairment analysis on Bison’s long-lived assets in connection with the termination of certain customer transportation agreements (refer to Note 6 - Revenues).

With the loss of future cash flows resulting from the contract terminations described above and the persistence of unfavorable market conditions which inhibited systems flows on the pipeline during the fourth quarter of 2018, the Partnership recognized an impairment charge of $537 million relating to the remaining carrying value of Bison’s property, plant and equipment after determining that it was no longer recoverable. The impairment charge was recorded under Impairment of long-lived assets line on the Consolidated statement of operations.