CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 0	$ 0
Accounts receivable, net	140	47
Accounts receivable from related companies	16	8
Exchanges receivable	11	6
Inventories	86	86
Other current assets	3	6
Total current assets	256	153
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment	3,358	3,349
Accumulated depreciation	(744)	(717)
Property, Plant and Equipment, Net, Total	2,614	2,632
Operating Lease, Right-of-Use Asset	4	5
Other non-current assets, net	171	169
Total assets	3,045	2,959
Liabilities, Current [Abstract]
Accounts Payable and Accrued Liabilities, Current	117	4
Accounts Payable, Related Parties, Current	20	14
Exchanges payable	65	71
Other Liabilities, Current	36	33
Liabilities, Current, Total	238	122
Long-term Debt and Lease Obligation	245	245
Notes Payable, Related Parties, Noncurrent	374	550
Operating Lease, Liability, Noncurrent	4	5
Other Liabilities, Noncurrent	258	243
Commitments and Contingencies
Partners' Capital [Abstract]
Partners' Capital	1,930	1,803
Accumulated Other Comprehensive Income (Loss), Net of Tax	(4)	(9)
Partners' Capital, Total	1,926	1,794
Liabilities and Equity, Total	$ 3,045	$ 2,959