VARIABLE INTEREST ENTITIES - Consolidated VIEs (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
ASSETS (LIABILITIES)
Cash and cash equivalents	$ 48	$ 33
Accounts receivable and other	39	42
Inventories	7	8
Other current assets	8	7
Equity investments	1,196	1,213
Property, plant and equipment, net	2,075	2,123
Other assets	13	3
Accounts payable and accrued liabilities	(30)	(31)
Provision for revenue sharing	(9)
Accounts payable to affiliates, net	(5)	(5)
Distributions payable		(1)
Accrued interest	(20)	(12)
Current portion of long-term debt	(36)	(51)
Long-term debt	(2,211)	(2,352)
Other liabilities	(29)	(29)
Consolidated VIEs | Restricted VIEs
ASSETS (LIABILITIES)
Cash and cash equivalents	13	19
Accounts receivable and other	26	30
Inventories	7	6
Other current assets	3	5
Equity investments	1,196	1,213
Property, plant and equipment, net	1,118	1,133
Other assets	1	1
Accounts payable and accrued liabilities	(21)	(24)
Provision for revenue sharing	(9)
Accounts payable to affiliates, net	(47)	(42)
Distributions payable		(1)
Accrued interest	(5)	(2)
Current portion of long-term debt	(36)	(51)
Long-term debt	(291)	(308)
Other liabilities	(27)	(26)
Deferred state income tax	$ (10)	$ (10)