Commitments and Contingencies - Schedule of Other Purchase Obligations (Details) (Other Purchase Obligations [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	$ 894
2015	336
2016	258
2017	150
2018	36
2019	30
Thereafter	84
Exelon Generation Co L L C [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	396	[1],[2]
2015	163	[1],[2]
2016	67	[1],[2]
2017	42	[1],[2]
2018	30	[1],[2]
2019	24	[1],[2]
Thereafter	70	[1],[2]
Commonwealth Edison Co [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	148	[3]
2015	63	[3]
2016	77	[3]
2017	1	[3]
2018	1	[3]
2019	1	[3]
Thereafter	5	[3]
PECO Energy Co [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	7	[3]
2015	3	[3]
2016	4	[3]
2017	0	[3]
2018	0	[3]
2019	0	[3]
Thereafter	0	[3]
Baltimore Gas and Electric Company [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	343	[3]
2015	107	[3]
2016	110	[3]
2017	107	[3]
2018	5	[3]
2019	5	[3]
Thereafter	$ 9	[3]

[1] Purchase obligations do not include commitments related to construction contracts. See Construction Commitments section below for additional information.

[2] Purchase obligations include commitments related to assets-held-for-sale. See Note 4 — Mergers, Acquisitions, and Dispositions for additional information.

[3] Purchase obligations include commitments related to smart meter installation. See Note 3 — Regulatory Matters for additional information.