PLANT, PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
PLANT, PROPERTY AND EQUIPMENT
Cost	$ 2,773	$ 2,760
Accumulated Depreciation	(892)	(811)
Net Book Value	1,881	1,949
Pipeline
PLANT, PROPERTY AND EQUIPMENT
Cost	2,091	2,086
Accumulated Depreciation	(701)	(638)
Net Book Value	1,390	1,448
Compression
PLANT, PROPERTY AND EQUIPMENT
Cost	519	516
Accumulated Depreciation	(148)	(134)
Net Book Value	371	382
Metering and other equipment
PLANT, PROPERTY AND EQUIPMENT
Cost	159	156
Accumulated Depreciation	(43)	(39)
Net Book Value	116	117
Construction in progress
PLANT, PROPERTY AND EQUIPMENT
Cost	4	2
Net Book Value	$ 4	$ 2