Debt and Credit Agreements Year-End (Tables)

12 Months Ended

Dec. 31, 2012

Debt Tables [Line Items]

Schedule Of Short Term Debt [Text Block]

	Maximum Program Size at December 31,				Outstanding Commercial Paper at December 31,				Average Interest Rate on Commercial Paper Borrowings for the Year Ended December 31,
Commercial Paper Issuer		2012 (a)		2011 (a)		2012		2011	2012		2011
Exelon Corporate	$	500	$	500	$	-	$	161	0.47	%	0.42	%
Generation		5,600		5,600		-		-	0.45	%	0.48	%
ComEd		1,000		1,000		-		-	0.50	%	0.71	%
PECO		600		600		-		-	-		-
BGE		600		400		-		-	0.43	%	0.38	%
Total	$	8,300	$	8,100	$	-	$	161

(a) Equals aggregate bank commitments under revolving and bilateral credit agreements. See discussion below and Credit Agreementstable below for items affecting effective program size.

Schedule Of Short Term Borrowing Activity [Text Block]

	2012			2011			2010
Average borrowings	$	199		$	218		$	125
Maximum borrowings outstanding		505			600			346
Average interest rates, computed on a daily basis		0.48	%		0.50	%		0.72	%
Average interest rates, at December 31		n.a.			0.44	%		n.a.
Generation
	2012			2011			2010
Average borrowings	$	4		$	51		$	0
Maximum borrowings outstanding		165			304			0
Average interest rates, computed on a daily basis		0.45	%		0.48	%		n.a.
Average interest rates, at December 31		n.a.			n.a.			n.a.
ComEd
	2012			2011			2010
Average borrowings	$	110		$	36		$	125
Maximum borrowings outstanding		366			407			346
Average interest rates, computed on a daily basis		0.50	%		0.71	%		0.72	%
Average interest rates, at December 31		n.a.			n.a.			n.a.
BGE
	2012			2011			2010
Average borrowings	$	6		$	26		$	1
Maximum borrowings outstanding		76			190			46
Average interest rates, computed on a daily basis		0.43	%		0.38	%		0.39	%
Average interest rates, computed at December 31		n.a.			n.a.			n.a.

Schedule Of Line Of Credit Facilities Text Block

							Available Capacity at December 31, 2012
Borrower	Aggregate Bank Commitment (a)		Facility Draws		Outstanding Letters of Credit		Actual		To Support Additional Commercial Paper
Exelon Corporate	$	500	$	—	$	2	$	498	$	498
Generation		5,600		—		1,818		3,782		3,782
ComEd		1,000		—		—		1,000		1,000
PECO		600		—		1		599		599
BGE		600		—		—		600		600
Total	$	8,300	$	—	$	1,821	$	6,479	$	6,479

(a)       Excludes additional credit facility agreements for Generation, ComEd, PECO and BGE with aggregate commitments of $50 million, $34 million, $34 million and $5 million, respectively, arranged with minority and community banks located primarily within ComEd's, PECO's and BGE's service territories. These facilities expire on October 19, 2013 and are solely for issuing letters of credit. As of December 31, 2012, letters of credit issued under these agreements totaled $23 million, $21 million, $21million and$1 million for Generation, ComEd, PECO and BGE, respectively.

Schedule Of Credit Agreement Covenants [Text Block]

	Exelon	Generation	ComEd	PECO	BGE
Credit facility threshold	2.50 to 1	3.00 to 1	2.00 to 1	2.00 to 1	2.00 to 1
At December 31, 2012, the interest coverage ratios at the Registrants were as follows:
	Exelon	Generation	ComEd	PECO	BGE
Interest coverage ratio	9.62	14.20	6.14	7.85	5.16

Schedule Of Debt Instruments Text Block

								Maturity	December 31,
			Rates					Date	2012		2011
Long-term debt
	First Mortgage Bonds (a) (b):
		Fixed rates	1.63	%	-	7.63	%	2012-2042	$	7,397	$	7,522
	Unsecured bonds:		2.80	%	-	6.35	%	2013-2036		1,850		—
	Rate stabilization bonds:		5.72	%	-	5.82	%	2017		332		—
	Senior unsecured notes		2.00	%	-	8.63	%	2014-2063		8,021		4,902
	Notes payable and other (c)		6.95	%	-	7.83	%	2012-2020		177		174
	Pollution control notes:
		Fixed rates	4.10	%	-	5.00	%	2014-2042		20		46
	Non-recourse debt:
		Fixed rates	2.33	%	-	5.50	%	2031-2037		238		—
		Variable rates	1.96	%	-	2.77	%	2014-2030		262		—
Total long-term debt										18,297		12,644
	Unamortized debt discount and premium, net									(17)		(32)
	Fair value adjustment									448		—
	Fair value hedge carrying value adjustment, net									17		15
	Long-term debt due within one year									(1,047)		(828)
Long-term debt									$	17,698	$	11,799
Long-term debt to financing trusts (d)
	Subordinated debentures to ComEd Financing III					6.35	%	2033	$	206	$	206
	Subordinated debentures to PECO Trust III					7.38	%	2028		81		81
	Subordinated debentures to PECO Trust IV					5.75	%	2033		103		103
	Subordinated debentures to BGE Trust					6.20	%	2043		258		—
Total long-term debt to financing trusts									$	648	$	390

(a)       Substantially all of ComEd's assets other than expressly excepted property and substantially all of PECO's assets are subject to the liens of their respective mortgage indentures.

(b)       Includes First Mortgage Bonds issued under the ComEd and PECO mortgage indentures securing pollution control bonds and notes.

(c)       Includes capital lease obligations of $30 million and$34million at December 31, 2012 and 2011, respectively. Lease payments of $3 million, $3 million, $3 million, $4 million, $4 million and $13 million will be made in 2013, 2014, 2015, 2016, 2017 and thereafter, respectively.

(d)       Amounts owed to these financing trusts are recorded as debt to financing trusts within Exelon's Consolidated Balance Sheets.

Schedule Of Maturities Of Long Term Debt [Text Block]

Year	Exelon			Generation		ComEd			PECO			BGE
2013	$	979		$	28	$	252		$	300		$	467
2014		1,483			616		617			250			70
2015		1,613			553		260			—			75
2016		1,041			76		665			—			379
2017		1,462			706		425			—			41
Thereafter		12,367	(a)		5,292		3,574	(b)		1,584	(c)		1,408	(d)
Total	$	18,945		$	7,271	$	5,793		$	2,134		$	2,440

(a)       Includes $648million due to ComEd, PECO and BGEfinancing trusts.

(b)       Includes $206 million due to ComEd financing trust.

(c)       Includes $184 million due to PECO financing trusts.

(d)       Includes $258 million due to BGE financing trust.

Exelon Generation Co L L C [Member]

Debt Tables [Line Items]

Schedule Of Debt Instruments Text Block

								Maturity	December 31,
			Rates					Date	2012		2011
Long-term debt
	Senior unsecured notes (b)		2.00	%	-	8.63	%	2014-2063	$	6,721	$	3,602
	Pollution control notes:
		Fixed rates	4.10	%	-	5.00	%	2014-2042		20		46
	Non-recourse debt:
		Fixed rates	2.33	%	-	5.50	%	2031-2037		238		—
		Variable rates	1.96	%	-	2.77	%	2014-2030		262		—
	Notes payable and other (a)					7.83	%	2012-2020		30		34
Total long-term debt										7,271		3,682
	Fair value adjustment (b)									199		—
	Unamortized debt discount and premium, net									13		(5)
	Long-term debt due within one year									(28)		(3)
Long-term debt									$	7,455	$	3,674

(a)       Includes Generation's capital lease obligations of $30 million and$34 million atDecember 31, 2012 and 2011, respectively. Generation will make lease payments of $3 million, $3 million, $3 million, $4 million, $4 million and $13 million in 2013, 2014, 2015, 2016, 2017 and thereafter, respectively.

(b) Includes $2,007 million of long-term debt to affiliate, comprised of $1,808 million senior unsecured notes and $199 million fair value adjustment.

Commonwealth Edison Co [Member]

Debt Tables [Line Items]

Schedule Of Debt Instruments Text Block

								Maturity	December 31,
			Rates					Date	2012		2011
Long-term debt
	First Mortgage Bonds (a) (b):
		Fixed rates	1.63	%	-	7.63	%	2012-2042	$	5,447	$	5,547
	Notes payable					6.95	%	2018		140		140
Total long-term debt										5,587		5,687
	Unamortized debt discount and premium, net									(20)		(22)
	Long-term debt due within one year									(252)		(450)
Long-term debt									$	5,315	$	5,215
Long-term debt to financing trust (c)
	Subordinated debentures to ComEd Financing III					6.35	%	2033	$	206	$	206

(a)       Substantially all of ComEd's assets other than expressly excepted property are subject to the lien of its mortgage indenture.

(b)       Includes First Mortgage Bonds issued under the ComEd mortgage indenture securing pollution control bonds and notes.

(c)       Amount owed to this financing trustis recorded as debt to financing trust within ComEd's Consolidated Balance Sheets.

PECO Energy Co [Member]

Debt Tables [Line Items]

Schedule Of Debt Instruments Text Block

								Maturity	December 31,
			Rates					Date	2012		2011
Long-term debt
	First Mortgage Bonds (a) (b):
		Fixed rates	2.38	%	-	5.95	%	2012-2037	$	1,950	$	1,975
Total long-term debt										1,950		1,975
	Unamortized debt discount and premium, net									(3)		(3)
	Long-term debt due within one year									(300)		(375)
Long-term debt									$	1,647	$	1,597
Long-term debt to financing trusts (c)
	Subordinated debentures to PECO Trust III					7.38	%	2028	$	81	$	81
	Subordinated debentures to PECO Trust IV					5.75	%	2033		103		103
Long-term debt to financing trusts									$	184	$	184

(a)       Substantially all of PECO's assets are subject to the lien of its mortgage indenture.

(b)       Includes First Mortgage Bonds issued under the PECO mortgage indenture securing pollution control bonds and notes.

(c)       Amount owed to this financing trust is recorded as debt to financing trust within PECO's Consolidated Balance Sheets.

Baltimore Gas and Electric Company [Member]

Debt Tables [Line Items]

Schedule Of Maturities Of Long Term Debt [Text Block]

								Maturity	December 31,
			Rates					Date	2012		2011
Long-term debt
		Unsecured bonds	2.80	%	-	6.35	%	2013-2036	$	1,850	$	1,710
		Rate stabilization bonds	5.47	%	-	5.82	%	2012-2017		332	$	395
Total long-term debt										2,182		2,105
	Unamortized debt discount and premium, net									(4)		(4)
	Long-term debt due within one year									(467)		(173)
Long-term debt									$	1,711	$	1,928
Long-term debt to financing trusts (a)
	Subordinated debentures to BGE Capital Trust II					6.20	%	2043	$	258	$	258
Long-term debt to financing trusts									$	258	$	258