PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
PROPERTY, PLANT AND EQUIPMENT
Cost	$ 2,639	$ 3,304
Accumulated Depreciation	(1,110)	(1,181)
Net Book Value	1,529	2,123
Pipeline
PROPERTY, PLANT AND EQUIPMENT
Cost	1,901	2,577
Accumulated Depreciation	(876)	(962)
Net Book Value	1,025	1,615
Compression
PROPERTY, PLANT AND EQUIPMENT
Cost	550	533
Accumulated Depreciation	(182)	(165)
Net Book Value	368	368
Metering and other
PROPERTY, PLANT AND EQUIPMENT
Cost	176	182
Accumulated Depreciation	(52)	(54)
Net Book Value	124	128
Construction in progress
PROPERTY, PLANT AND EQUIPMENT
Cost	12	12
Net Book Value	$ 12	$ 12