PROPERTY, PLANT AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2018

Property, plant and equipment [abstract]

Disclosure of detailed information about property, plant and equipment

($ millions)	Land and Land Rights		Pipelines		Facilities and Equipment		Cavern Storage and Other		Assets Under Construction		Total
Cost
Balance at December 31, 2016	218		4,253		5,514		1,089		1,965		13,039
Additions and transfers	70		1,895		1,230		133		(1,428	)	1,900
Acquisition (Note 6)	41		448		—		—		123		612
Change in decommissioning provision	—		63		(21	)	—		—		42
Disposals and other	—		(9	)	(8	)	1		(1	)	(17	)
Balance at December 31, 2017	329		6,650		6,715		1,223		659		15,576
Additions and transfers	12		531		469		231		291		1,534
Change in decommissioning provision	—		(10	)	5		19		—		14
Disposals and other	(1	)	(7	)	(30	)	5		(11	)	(44	)
Balance at December 31, 2018	340		7,164		7,159		1,478		939		17,080
Depreciation
Balance at December 31, 2016	7		966		575		160		—		1,708
Depreciation	2		136		148		48		—		334
Disposals and other	—		(6	)	(2	)	(4	)	—		(12	)
Balance at December 31, 2017	9		1,096		721		204		—		2,030
Depreciation	3		142		164		55		—		364
Disposals and other	—		(17	)	(18	)	(9	)	—		(44	)
Balance at December 31, 2018	12		1,221		867		250		—		2,350
Carrying amounts
Balance at December 31, 2017	320		5,554		5,994		1,019		659		13,546
Balance at December 31, 2018	328		5,943		6,292		1,228		939		14,730