Revenue Recognition and Allowance for Credit Losses - Summary of Contract Assets and Liabilities (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Accounts Receivable
Opening balance as of December 31, 2022	$ 858
Closing balance as of September 30, 2023	733
Increase (decrease) in accounts receivable	(125)
Other Accrued Unbilled Revenues
Opening balance as of December 31, 2022	764
Closing balance as of September 30, 2023	340
Increase (decrease) in other accrued unbilled revenues	(424)
Contract Assets
Opening balance as of December 31, 2022	4
Closing balance as of September 30, 2023	0
Decrease in contract assets	(4)
Contract Liabilities
Opening balance as of December 31, 2022	45
Closing balance as of September 30, 2023	5
Increase (decrease) in contract liabilities	(40)
Revenue recognized included in the opening contract liability for the period	2
Houston Electric
Accounts Receivable
Opening balance as of December 31, 2022	271
Closing balance as of September 30, 2023	459
Increase (decrease) in accounts receivable	188
Other Accrued Unbilled Revenues
Opening balance as of December 31, 2022	142
Closing balance as of September 30, 2023	182
Increase (decrease) in other accrued unbilled revenues	40
Contract Liabilities
Opening balance as of December 31, 2022	2
Closing balance as of September 30, 2023	5
Increase (decrease) in contract liabilities	3
Revenue recognized included in the opening contract liability for the period	2
CERC
Accounts Receivable
Opening balance as of December 31, 2022	478
Closing balance as of September 30, 2023	230
Increase (decrease) in accounts receivable	(248)
Other Accrued Unbilled Revenues
Opening balance as of December 31, 2022	573
Closing balance as of September 30, 2023	119
Increase (decrease) in other accrued unbilled revenues	$ (454)