Financing Activities (Details) (USD $)					9 Months Ended							9 Months Ended				1 Months Ended		1 Months Ended	9 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Dec. 31, 2009	Sep. 30, 2011 Constellation Energy;	Sep. 30, 2011 Constellation Energy; Syndicated Revolver October 2013	Sep. 30, 2011 Constellation Energy; Commodity-linked August 2014	Sep. 30, 2011 Constellation Energy; Bilateral September 2014	Sep. 30, 2011 Constellation Energy; Bilateral December 2014	Sep. 30, 2011 Constellation Energy; Bilateral June 2014	Sep. 30, 2011 Constellation Energy; Bilateral September 2013	Sep. 30, 2011 Baltimore Gas and Electric Company	Dec. 31, 2010 Baltimore Gas and Electric Company	Sep. 30, 2010 Baltimore Gas and Electric Company	Dec. 31, 2009 Baltimore Gas and Electric Company	Jul. 31, 2011 Subsidiary of Constellation Energy year	Sep. 30, 2011 Subsidiary of Constellation Energy	Jul. 31, 2011 Subsidiary of Constellation Energy Project financing mW	Sep. 30, 2011 Subsidiary of Constellation Energy Project financing year	Sep. 30, 2011 Revolving credit facility expiring in 2015	Sep. 30, 2011 Amended and extended existing reserve based lending facility Ratio	Jul. 31, 2011 Amended and extended existing reserve based lending facility	Jan. 31, 2011 7.00% Fixed-Rate Notes, due April 1, 2012	Jan. 31, 2011 5.15% Fixed-Rate Notes, due December 1, 2020
Credit facilities
Bank lines of credit under committed credit facilities					$ 4,200,000,000	$ 2,500,000,000	$ 500,000,000	$ 550,000,000	$ 250,000,000	$ 250,000,000	$ 150,000,000					$ 150,000,000		$ 40,000,000		$ 600,000,000		$ 150,000,000
Letters of credit issued including the commodities linked credit facility					1,600,000,000
Line of credit facility adjusted borrowing capacity							500,000,000
Term of senior secured credit facility (in years)																3
Maximum amount up to which amount committed under senior credit facility may be increased																200,000,000						500,000,000
Amount borrowed under line of credit facility																	130,000,000				72,000,000
Current ratio to be maintained, numerator																					1
Current ratio to be maintained, denominator																					1
Short-term notes outstanding	160,600,000	32,400,000			20,600,000							140,000,000
Short-term notes outstanding weighted average interest rate (as a percent)					6.54%
Commercial paper, weighted average interest rate (as a percent)												0.37%
Solar facility (MW)																		30
Term of variable rate note for solar facility (in years)																			19
Notional amount of interest rate swaps																30,000,000
Bridge loan																26,000,000
Equity bridge loan																28,000,000
Debt
Retirement of aggregate principal amount of fixed term notes																							213,500,000
Long-term debt																								550,000,000
Loss on redemption of 7.00% fixed-rate notes due April 1, 2012, pre-tax																							5,000,000
Interest rate (as a percent)																							7.00%	5.15%
Net available liquidity
Credit facilities					3,700,000,000		500,000,000					600,000,000
Less: Letters of credit issued					(1,200,000,000)		(400,000,000)
Undrawn facilities					2,500,000,000							600,000,000
Less: Commercial paper outstanding												(100,000,000)
Net available facilities					2,500,000,000							500,000,000
Add: Cash and cash equivalents					1,100,000,000
Net available liquidity					3,600,000,000							500,000,000
Cash and cash equivalents	$ 1,171,000,000	$ 2,028,500,000	$ 1,295,200,000	$ 3,440,000,000								$ 51,300,000	$ 50,000,000	$ 250,500,000	$ 13,600,000
Credit Facility Compliance and Covenants
Credit facilities, required debt-capitalization ratio percentage (as a percent)					65.00%							65.00%
Credit facilities, calculated debt-capitalization ratio percentage (as a percent)					36.00%							45.00%