Revenue Recognition and Allowance for Credit Losses - Summary of Contract Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Accounts Receivable
Opening balance as of December 31, 2022		$ 858
Closing balance as of June 30, 2023	$ 608	608
Increase (decrease) in accounts receivable		(250)
Other Accrued Unbilled Revenues
Opening balance as of December 31, 2022		764
Closing balance as of June 30, 2023	289	289
Increase (decrease) in other accrued unbilled revenues		(475)
Contract Assets
Opening balance as of December 31, 2022		4
Closing balance as of June 30, 2023	0	0
Decrease in contract assets		(4)
Contract Liabilities
Opening balance as of December 31, 2022		45
Closing balance as of June 30, 2023	6	6
Increase (decrease) in contract liabilities		(39)
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 June 30, 2023	306	306
Increase (decrease) in accounts receivable		35
Other Accrued Unbilled Revenues
Opening balance as of December 31, 2022		142
Closing balance as of June 30, 2023	136	136
Increase (decrease) in other accrued unbilled revenues		(6)
Contract Liabilities
Opening balance as of December 31, 2022		2
Closing balance as of June 30, 2023	6	6
Increase (decrease) in contract liabilities		4
Revenue recognized included in the opening contract liability for the period	1
CERC
Accounts Receivable
Opening balance as of December 31, 2022		478
Closing balance as of June 30, 2023	267	267
Increase (decrease) in accounts receivable		(211)
Other Accrued Unbilled Revenues
Opening balance as of December 31, 2022		573
Closing balance as of June 30, 2023	$ 117	117
Increase (decrease) in other accrued unbilled revenues		$ (456)