Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Debt and Credit Agreements - Schedule of Outstanding Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt, gross	$ 36,516	$ 35,560
Unamortized debt discount and premium, net	77	72
Unamortized debt issuance costs	(248)	(214)
Long-term debt	35,093	31,329
Junior subordinated notes
Debt Instrument [Line Items]
Long-term debt, gross	1,150	1,150
Senior unsecured notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 10,585	10,685
Maximum [Member] \| Junior subordinated notes
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.50%
Maximum [Member] \| Senior unsecured notes
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	7.60%
Minimum [Member] \| Senior unsecured notes
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.45%
Exelon Corporate [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 7,589	7,039
Unamortized debt discount and premium, net	(10)	(7)
Unamortized debt issuance costs	(47)	(39)
Fair value adjustment	186	182
Long-term debt due within one year	(300)	(1,458)
Long-term debt	7,418	5,717
Exelon Corporate [Member] \| Junior subordinated notes
Debt Instrument [Line Items]
Long-term debt, gross	1,150	1,150
Exelon Corporate [Member] \| Senior unsecured notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 6,439	$ 5,889
Exelon Corporate [Member] \| Maximum [Member] \| Junior subordinated notes
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.50%
Exelon Corporate [Member] \| Maximum [Member] \| Senior unsecured notes
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	7.60%
Exelon Corporate [Member] \| Minimum [Member] \| Senior unsecured notes
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.45%

Outstanding fair value adjustment related to purchase accounting.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt classified as other, payable within one year or the operating cycle, if longer.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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