Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Debt and Credit Agreements - Schedule of Debt Maturities (Details) $ in Millions	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
2017	$ 2,075
2018	959
2019	3,564
2020	1,513
2021	3,084
Thereafter	22,852	[1]
Total	34,047
Exelon Corporate [Member]
Debt Instrument [Line Items]
2017	0
2018	0
2019	1,450
2020	300
2021	1,150
Thereafter	4,139
Total	$ 7,039

[1] Includes $390 million due to ComEd and PECO financing trusts.