VARIABLE INTEREST ENTITIES - Consolidated VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
ASSETS (LIABILITIES)
Cash and cash equivalents	$ 52	$ 33
Accounts receivable and other	41	48
Inventories	9	8
Other current assets	5	8
Equity investments	1,196	1,196
Property, plant and equipment, net	1,522	1,529
Other assets	3	6
Accounts payable and accrued liabilities	(29)	(36)
Accounts payable to affiliates, net	(7)	(6)
Accrued interest	(20)	(12)
Current portion of long-term debt	(36)	(36)
Long-term debt	(2,040)	(2,072)
Other liabilities	(31)	(29)
Consolidated VIEs | Restricted VIEs
ASSETS (LIABILITIES)
Cash and cash equivalents	25	16
Accounts receivable and other	37	39
Inventories	9	8
Other current assets	5	6
Equity investments	1,196	1,196
Property, plant and equipment, net	1,237	1,240
Other assets	1	1
Accounts payable and accrued liabilities	(26)	(33)
Accounts payable to affiliates, net	(38)	(40)
Accrued interest	(5)	(2)
Current portion of long-term debt	(36)	(36)
Long-term debt	(349)	(341)
Other liabilities	(28)	(27)
Deferred state income tax	$ (9)	$ (9)