Revenue - Narrative (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Revenues	[1]	$ 3,475		$ 3,124	$ 9,282	$ 8,472
Incremental decrease to uncollectible expense due to Covid-19			$ 25
Deferred Regulatory Assets
Disaggregation of Revenue [Line Items]
Incremental decrease to uncollectible expense due to Covid-19			$ 15
Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges					29	27
Other Non-Customer Revenue | Derivative revenue
Disaggregation of Revenue [Line Items]
Late payment charges		10		9
Revenues		$ 2		$ 3	$ 13	$ 5

[1] Includes excise and gross receipts tax collections of $111 million and $103 million during the three months ended September 30, 2022 and 2021, respectively, and $305 million and $283 million during the nine months ended September 30, 2022 and 2021, respectively.