CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY AND COMPREHENSIVE INCOME (LOSS) (Constellation Energy Group, Inc. and Subsidiaries) (USD $) In Millions, except Share data, unless otherwise specified	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests	Comprehensive Income
Balance at Dec. 31, 2008	$ 3,391.5	$ 3,164.5	$ 2,228.7	$ (2,211.8)	$ 210.1
Balance (in shares) at Dec. 31, 2008		199,129,000
Increase (Decrease) in Shareholders' Equity
Contribution from noncontrolling interest	8.0				8.0
Other noncontrolling interest activity	0.4				0.4
Comprehensive Income (Loss)
Net (loss) income	4,503.4		4,443.4		60.0	4,503.4
Hedging instruments:
Reclassification of net losses on hedging instruments from OCI to net income, net of taxes of $(106.4), $(347.5) and $(898.5) during 2011, 2010 and 2009, respectively	1,499.4			1,499.4		1,499.4
Net unrealized loss on hedging instruments, net of taxes of $210.7, $134.6 and $251.2 during 2011, 2010 and 2009, respectively	(474.7)			(474.7)		(474.7)
Available-for-sale securities:
Reclassification of net (gains) losses on securities from OCI to net income, net of taxes of $0.1, and $(24.6) during 2010 and 2009, respectively	25.4			25.4		25.4
Net unrealized gains (losses) on securities, net of taxes of $0.3, $(0.1), $(78.2) during 2011, 2010 and 2009, respectively	77.7			77.7		77.7
Defined benefit plans:
Prior service cost arising during period, net of taxes of $0.3, $(1.1) and $1.0 during 2011, 2010 and 2009, respectively	(1.5)			(1.5)		(1.5)
Net gains (losses) arising during period, net of taxes of $68.8, $31.3 and $(23.9) during 2011, 2010 and 2009, respectively	26.9			26.9		26.9
Amortization of net actuarial loss, prior service cost, and transition obligation included in net periodic benefit cost, net of taxes of $(19.8), $(15.5) and $(19.8) during 2011, 2010 and 2009, respectively	30.3			30.3		30.3
Deconsolidation of CENG joint venture:
Net unrealized gains on nuclear decommissioning trust funds, net of taxes of $125.3	(125.3)			(125.3)		(125.3)
Net unrealized losses on defined benefit plans, net of taxes of $(94.6)	138.0			138.0		138.0
Net unrealized gains (losses) on foreign currency translation, net of taxes of $-, $2.2 and $(2.7) during 2011, 2010 and 2009, respectively	7.1			7.1		7.1
Other comprehensive income (loss) - equity investment in CENG, net of taxes of $4.1, $(14.1) and $(11.7) during 2011, 2010 and 2009, respectively	12.9			12.9		12.9
Other comprehensive income (loss) related to other equity method investees, net of taxes of $6.0, $0.3 and $(1.3) during 2011, 2010 and 2009, respectively	2.1			2.1		2.1
Total Comprehensive Income (Loss)	5,721.7		4,443.4	1,218.3	60.0	5,721.7
BGE preference stock dividends	(13.2)				(13.2)
Common stock dividend declared ($0.96 per share)	(192.2)		(192.2)
Common stock issued and share-based awards	46.2	65.1	(18.9)
Common stock issued and share-based awards (in shares)		1,856,000
Balance at Dec. 31, 2009	8,962.4	3,229.6	6,461.0	(993.5)	265.3
Balance (in shares) at Dec. 31, 2009		200,985,000
Increase (Decrease) in Shareholders' Equity
Sale of noncontrolling interest	(17.6)				(17.6)
Distribution from noncontrolling interest	(6.3)				(6.3)
Other noncontrolling interest activity	(0.2)				(0.2)
Comprehensive Income (Loss)
Net (loss) income	(931.8)		(982.6)		50.8	(931.8)
Hedging instruments:
Reclassification of net losses on hedging instruments from OCI to net income, net of taxes of $(106.4), $(347.5) and $(898.5) during 2011, 2010 and 2009, respectively	582.4			582.4		582.4
Net unrealized loss on hedging instruments, net of taxes of $210.7, $134.6 and $251.2 during 2011, 2010 and 2009, respectively	(233.2)			(233.2)		(233.2)
Available-for-sale securities:
Reclassification of net (gains) losses on securities from OCI to net income, net of taxes of $0.1, and $(24.6) during 2010 and 2009, respectively	(0.1)			(0.1)		(0.1)
Net unrealized gains (losses) on securities, net of taxes of $0.3, $(0.1), $(78.2) during 2011, 2010 and 2009, respectively	0.1			0.1		0.1
Defined benefit plans:
Prior service cost arising during period, net of taxes of $0.3, $(1.1) and $1.0 during 2011, 2010 and 2009, respectively	1.6			1.6		1.6
Transition obligation arising during the period, net of taxes of $(0.2) during 2010	0.4			0.4		0.4
Net gains (losses) arising during period, net of taxes of $68.8, $31.3 and $(23.9) during 2011, 2010 and 2009, respectively	(56.6)			(56.6)		(56.6)
Amortization of net actuarial loss, prior service cost, and transition obligation included in net periodic benefit cost, net of taxes of $(19.8), $(15.5) and $(19.8) during 2011, 2010 and 2009, respectively	22.7			22.7		22.7
Deconsolidation of CENG joint venture:
Net unrealized gains (losses) on foreign currency translation, net of taxes of $-, $2.2 and $(2.7) during 2011, 2010 and 2009, respectively	(6.2)			(6.2)		(6.2)
Other comprehensive income (loss) - equity investment in CENG, net of taxes of $4.1, $(14.1) and $(11.7) during 2011, 2010 and 2009, respectively	9.6			9.6		9.6
Other comprehensive income (loss) related to other equity method investees, net of taxes of $6.0, $0.3 and $(1.3) during 2011, 2010 and 2009, respectively	(0.5)			(0.5)		(0.5)
Total Comprehensive Income (Loss)	(611.6)		(982.6)	320.2	50.8	(611.6)
BGE preference stock dividends	(13.2)				(13.2)
Common stock dividend declared ($0.96 per share)	(193.8)		(193.8)
Common stock issued and share-based awards	63.6	77.4	(13.8)
Common stock issued and share-based awards (in shares)		1,304,000
Common stock returned in connection with comprehensive agreement with EDF	(75.3)	(75.3)
Common stock returned in connection with comprehensive agreement with EDF (in shares)		(2,500,000)
Balance at Dec. 31, 2010	8,108.0	3,231.7	5,270.8	(673.3)	278.8
Balance (in shares) at Dec. 31, 2010	199,788,658	199,789,000
Increase (Decrease) in Shareholders' Equity
Other noncontrolling interest activity	7.8				7.8
Comprehensive Income (Loss)
Net (loss) income	(306.8)		(340.3)		33.5	(306.8)
Hedging instruments:
Reclassification of net losses on hedging instruments from OCI to net income, net of taxes of $(106.4), $(347.5) and $(898.5) during 2011, 2010 and 2009, respectively	180.8			180.8		180.8
Net unrealized loss on hedging instruments, net of taxes of $210.7, $134.6 and $251.2 during 2011, 2010 and 2009, respectively	(346.0)			(346.0)		(346.0)
Available-for-sale securities:
Net unrealized gains (losses) on securities, net of taxes of $0.3, $(0.1), $(78.2) during 2011, 2010 and 2009, respectively	(0.6)			(0.6)		(0.6)
Defined benefit plans:
Prior service cost arising during period, net of taxes of $0.3, $(1.1) and $1.0 during 2011, 2010 and 2009, respectively	(0.5)			(0.5)		(0.5)
Net gains (losses) arising during period, net of taxes of $68.8, $31.3 and $(23.9) during 2011, 2010 and 2009, respectively	(105.9)			(105.9)		(105.9)
Amortization of net actuarial loss, prior service cost, and transition obligation included in net periodic benefit cost, net of taxes of $(19.8), $(15.5) and $(19.8) during 2011, 2010 and 2009, respectively	29.2			29.2		29.2
Deconsolidation of CENG joint venture:
Net unrealized gains (losses) on foreign currency translation, net of taxes of $-, $2.2 and $(2.7) during 2011, 2010 and 2009, respectively	(1.5)			(1.5)		(1.5)
Other comprehensive income (loss) - equity investment in CENG, net of taxes of $4.1, $(14.1) and $(11.7) during 2011, 2010 and 2009, respectively	(8.7)			(8.7)		(8.7)
Other comprehensive income (loss) related to other equity method investees, net of taxes of $6.0, $0.3 and $(1.3) during 2011, 2010 and 2009, respectively	(9.8)			(9.8)		(9.8)
Total Comprehensive Income (Loss)	(569.8)		(340.3)	(263.0)	33.5	(569.8)
BGE preference stock dividends	(13.2)				(13.2)
Common stock dividend declared ($0.96 per share)	(192.4)		(192.4)
Common stock issued and share-based awards	60.4	60.5	(0.1)
Common stock issued and share-based awards (in shares)		1,897,000
Balance at Dec. 31, 2011	$ 7,400.8	$ 3,292.2	$ 4,738.0	$ (936.3)	$ 306.9
Balance (in shares) at Dec. 31, 2011	201,686,291	201,686,000