Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Debt and Credit Agreements - Narrative (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 24, 2022	Dec. 31, 2021	Feb. 01, 2022	Jan. 21, 2022	Dec. 31, 2020
Line of Credit Facility [Line Items]
Long-term debt, gross		$ 38,366			$ 36,516
Subsequent Event [Member]
Line of Credit Facility [Line Items]
Short-Term Loans				$ 2,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		10,331
Line of credit facility, remaining borrowing capacity		7,948
Commercial Paper
Line of Credit Facility [Line Items]
Commercial Paper		1,301			1,031
Line of credit facility, maximum borrowing capacity		9,000			9,000
Corporate, Non-Segment [Member]
Line of Credit Facility [Line Items]
Long-term debt, gross		7,289			7,589
Corporate, Non-Segment [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		600
Line of credit facility, remaining borrowing capacity		594
Corporate, Non-Segment [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			$ 900
Corporate, Non-Segment [Member] | ShortTermDebt03232017 [Member]
Line of Credit Facility [Line Items]
Short-Term Loans		500
Corporate, Non-Segment [Member] | ShortTermDebt03242021 [Member]
Line of Credit Facility [Line Items]
Short-Term Loans		200
Corporate, Non-Segment [Member] | ShortTermDebt03312021.2 [Member]
Line of Credit Facility [Line Items]
Short-Term Loans		150
Corporate, Non-Segment [Member] | ShortTermDebt03312021.1 [Member]
Line of Credit Facility [Line Items]
Short-Term Loans		150
Corporate, Non-Segment [Member] | ShortTermDebt01242022 | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Short-Term Loans	$ 1,150
Corporate, Non-Segment [Member] | Commercial Paper
Line of Credit Facility [Line Items]
Commercial Paper		0			0
Line of credit facility, maximum borrowing capacity		$ 600			$ 600
Corporate, Non-Segment [Member] | London Interbank Offered Rate (LIBOR) [Member] | ShortTermDebt03232017 [Member]
Line of Credit Facility [Line Items]
Short-Term Loans, Interest rate terms		0.65
Corporate, Non-Segment [Member] | London Interbank Offered Rate (LIBOR) [Member] | ShortTermDebt03242021 [Member]
Line of Credit Facility [Line Items]
Short-Term Loans, Interest rate terms		0.65
Corporate, Non-Segment [Member] | London Interbank Offered Rate (LIBOR) [Member] | ShortTermDebt03312021.2 [Member]
Line of Credit Facility [Line Items]
Short-Term Loans, Interest rate terms		0.65
Corporate, Non-Segment [Member] | London Interbank Offered Rate (LIBOR) [Member] | ShortTermDebt03312021.1 [Member]
Line of Credit Facility [Line Items]
Short-Term Loans, Interest rate terms		0.65
Corporate, Non-Segment [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of credit facility, interest rate at period end			1.275%
Corporate, Non-Segment [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | ShortTermDebt01242022 | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Short-Term Loans, Interest rate terms	0.75