CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING ACTIVITIES
Net income	$ 1,707	$ 1,827	$ 1,665
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,315	1,364	1,436
Deferred income taxes	41	100	48
Provision for uncollectible accounts	66	51	60
Accrued interest on affiliate note	61	61	43
Net loss on early retirement of debt	63	0	30
Changes in current assets and liabilities:
Accounts receivable	88	(19)	40
Accounts payable	(58)	(50)	69
Accrued income and other taxes	1	(46)	(34)
Other current assets and liabilities, net	(220)	60	40
Other current assets and liabilities - affiliates, net	0	1	8
Changes in other noncurrent assets and liabilities, net	52	15	473
Changes in affiliate obligations, net	(70)	(49)	(105)
Other, net	25	17	18
Net cash provided by operating activities	3,071	3,332	3,791
INVESTING ACTIVITIES
Capital expenditures	(1,091)	(1,055)	(1,040)
Changes in advances to affiliates	1,842
Payments for advance to affiliate		(694)	(119)
Proceeds from sale of property, plant and equipment and other assets	3	26	6
Net cash provided by (used in) investing activities	754	(1,723)	(1,153)
FINANCING ACTIVITIES
Net proceeds from issuance of long-term debt	115	0	0
Payments of long-term debt	(2,796)	(12)	(1,359)
Dividends paid	(1,725)	(1,600)	(1,275)
Changes in advances from affiliates	592	0	0
Net cash used in financing activities	(3,814)	(1,612)	(2,634)
Net increase (decrease) in cash, cash equivalents and restricted cash	11	(3)	4
Cash, cash equivalents and restricted cash at beginning of period	4	7	3
Cash, cash equivalents and restricted cash at end of period	15	4	7
Supplemental cash flow information:
Income taxes (paid) refunded, net	(556)	(539)	8
Interest paid (net of capitalized interest of $29, $27 and $24)	(310)	(378)	(466)
Cash, cash equivalents and restricted cash:
Total	$ 4	$ 4	$ 3