TRANSACTIONS WITH MAJOR CUSTOMERS (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Transactions with major customers
Revenues	$ 89	$ 83	$ 85	$ 87	$ 87	$ 80	$ 82	$ 87	$ 344	$ 336	$ 341	[1]
Trade accounts receivable	31				30				31	30
Total revenues | Customer concentration risk | Anadarko Energy Services Company
Transactions with major customers
Revenues									48	48	48
Total revenues | Customer concentration risk | Pacific Gas and Electric Company
Transactions with major customers
Revenues									42	45	$ 46
Accounts receivable and other | Amounts owed by major customers | Anadarko Energy Services Company
Transactions with major customers
Trade accounts receivable	4				4				4	4
Accounts receivable and other | Amounts owed by major customers | Pacific Gas and Electric Company
Transactions with major customers
Trade accounts receivable	$ 3				$ 4				$ 3	$ 4

[1] Recast as discussed in Note 2 and Note 6.