Leases - Components of Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Components of Lease Cost [Line Items]
Operating lease costs	$ 58	$ 66	$ 84
Variable lease costs	9	8	7
Total lease costs	67	74	91
Sublease Income	$ 4	$ 4	4
Operating Lease, Weighted Average Remaining Lease Term	8 years 9 months 18 days	9 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent	4.00%	3.90%
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 35	$ 46	1
Commonwealth Edison Co
Schedule of Components of Lease Cost [Line Items]
Operating lease costs	1	2	3
Variable lease costs	1	1	1
Total lease costs	$ 2	$ 3	4
Operating Lease, Weighted Average Remaining Lease Term	1 year 9 months 18 days	1 year
Operating Lease, Weighted Average Discount Rate, Percent	0.70%	2.60%
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 0	$ 0	0
PECO Energy Co
Schedule of Components of Lease Cost [Line Items]
Operating lease costs	0	0	0
Variable lease costs	0	0	0
Total lease costs	$ 0	$ 0	0
Operating Lease, Weighted Average Remaining Lease Term	5 years	5 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent	2.50%	2.30%
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 0	$ 0	0
Baltimore Gas and Electric Company
Schedule of Components of Lease Cost [Line Items]
Operating lease costs	5	15	30
Variable lease costs	0	0	1
Total lease costs	$ 5	$ 15	31
Operating Lease, Weighted Average Remaining Lease Term	17 years 1 month 6 days	70 years 10 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	5.00%	4.50%
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 32	$ 0	(1)
Pepco Holdings LLC
Schedule of Components of Lease Cost [Line Items]
Operating lease costs	43	42	43
Variable lease costs	3	2	1
Total lease costs	46	44	44
Sublease Income	4	4	4
Amortization of ROU asset	16	14	11
Interest on lease liabilities	6	4	2
Total finance lease cost	$ 22	$ 18	13
Operating Lease, Weighted Average Remaining Lease Term	6 years 1 month 6 days	6 years 9 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	4 years 10 months 24 days	5 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent	4.20%	4.20%
Finance Lease, Weighted Average Discount Rate, Percent	2.70%	2.30%
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 3	$ 2	1
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	11	14	32
Potomac Electric Power Company
Schedule of Components of Lease Cost [Line Items]
Operating lease costs	11	10	10
Variable lease costs	1	1	0
Total lease costs	12	11	10
Amortization of ROU asset	6	5	4
Interest on lease liabilities	2	1	1
Total finance lease cost	$ 8	$ 6	5
Operating Lease, Weighted Average Remaining Lease Term	7 years 7 months 6 days	8 years 1 month 6 days
Finance Lease, Weighted Average Remaining Lease Term	4 years 10 months 24 days	5 years 4 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	4.10%	4.00%
Finance Lease, Weighted Average Discount Rate, Percent	2.70%	2.30%
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 0	$ 0	0
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	5	4	12
Delmarva Power & Light Company
Schedule of Components of Lease Cost [Line Items]
Operating lease costs	11	12	12
Variable lease costs	1	1	0
Total lease costs	12	13	12
Sublease Income	4	4	4
Amortization of ROU asset	6	6	4
Interest on lease liabilities	2	2	1
Total finance lease cost	$ 8	$ 8	5
Operating Lease, Weighted Average Remaining Lease Term	7 years 4 months 24 days	7 years 10 months 24 days
Finance Lease, Weighted Average Remaining Lease Term	4 years 9 months 18 days	5 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent	4.00%	4.00%
Finance Lease, Weighted Average Discount Rate, Percent	2.60%	2.30%
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 1	$ 1	1
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	3	7	12
Atlantic City Electric Company
Schedule of Components of Lease Cost [Line Items]
Operating lease costs	6	6	6
Variable lease costs	1	1	0
Total lease costs	7	7	6
Amortization of ROU asset	4	3	3
Interest on lease liabilities	1	1	0
Total finance lease cost	$ 5	$ 4	3
Operating Lease, Weighted Average Remaining Lease Term	3 years 2 months 12 days	3 years 3 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	5 years 1 month 6 days	5 years 7 months 6 days
Operating Lease, Weighted Average Discount Rate, Percent	3.60%	3.30%
Finance Lease, Weighted Average Discount Rate, Percent	2.80%	2.40%
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 2	$ 1	0
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 3	$ 3	$ 8