ACCOUNTS RECEIVABLE AND OTHER (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
ACCOUNTS RECEIVABLE AND OTHER
Trade accounts receivable, net of allowance of nil	$ 37	$ 40
Imbalance receivable from affiliates	1	1
Other	1	1
Accounts receivable and other	39	42
Trade accounts receivable, allowance	$ 0	$ 0