Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Operating revenues [Abstract]
Revenues	$ 29,447	$ 27,429		$ 24,888
Operating revenues	18,395	16,637		14,277
Electric Revenue	9,876	9,467		9,365
Gas Domestic Regulated Revenue	1,176	1,325		1,246
Operating revenues from affiliates	9	23		70
Regulated Operating Revenue	11,052	10,792		10,611
Reclassifications from accumulated OCI to net income	18,395	16,637		14,277
Operating expenses
Rate-regulated utility purchased power and fuel	3,077	3,103		2,540
Purchased power	10,007	9,369		6,928
Purchased power and fuel from affiliates	0	531		1,256
Operating and maintenance	8,322	8,568		7,270
Depreciation and amortization	2,450	2,314		2,153
Taxes other than income	1,200	1,154		1,095
Total operating expenses	25,056	25,039		21,242
Equity in (losses) earnings of unconsolidated affiliates		(20)		10
Gain on sales of assets	18	437		13
Gain on consolidation and acquisition of businesses	0	289		0
Operating Income (Loss)	4,409	3,096		3,669
Other income and (deductions)
Interest expense, net	(992)	(1,024)		(1,315)
Interest expense to affiliates, net	(41)	(41)		(41)
Other, net	(46)	455		460
Total other income and (deductions)	(1,079)	(610)		(896)
Income before income taxes	3,330	2,486		2,773
Income before income taxes	3,330	2,486		2,773
Income taxes	1,073	666		1,044
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions	(7)	(20)		10
Net income	2,250	1,820		1,729
Net income (loss) attributable to noncontrolling interest and preference stock dividends	19	(197)		(10)
Net income attributable to common shareholders	2,269	1,623		1,719
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost, net of tax	(46)	(30)		0
Actuarial loss reclassified to periodic cost, net of tax	220	147		208
Pension and non-pension postretirement benefit plans valuation adjustment, net of tax	(99)	(497)		669
Unrealized gain (loss) on cash flow hedges, net of taxes	9	(148)		(248)
Unrealized gain (loss) on marketable securities, net of taxes	0	1		2
Unrealized gain (loss) on equity investments, net of taxes	(3)	8		106
Unrealized gain (loss) on foreign currency translation, net of taxes	(21)	(9)		(10)
Reversal of CENG equity method AOCI, net of taxes	0	(116)		0
Other comprehensive income (loss)	60	(644)	[1]	727
Comprehensive income	$ 2,310	$ 1,176		$ 2,456
Average shares of common stock outstanding:
Basic	890	860		856
Diluted	893	864		860
Earnings per average common share:
Basic (in usd per share)	$ 2.55	$ 1.89		$ 2.01
Diluted (in usd per share)	2.54	1.88		2.00
Dividends per common share (in usd per share)	$ 1.24	$ 1.24		$ 1.46
Exelon Generation Co L L C [Member]
Operating revenues [Abstract]
Revenues	$ 19,135	$ 17,393		$ 15,630
Operating revenues	18,386	16,614		14,207
Operating revenues from affiliates	749	779		1,423
Reclassifications from accumulated OCI to net income	18,386	16,614		14,207
Operating expenses
Rate-regulated utility purchased power and fuel	10,007	9,368		6,927
Purchased power and fuel from affiliates	14	557		1,270
Operating and maintenance	4,688	4,943		3,960
Operating and maintenance from affiliates	620	623		574
Depreciation and amortization	1,054	967		856
Taxes other than income	489	465		389
Total operating expenses	16,872	16,923		13,976
Equity in (losses) earnings of unconsolidated affiliates	8	(20)		10
Gain on sales of assets	12	437		13
Gain on consolidation and acquisition of businesses	0	289		0
Operating Income (Loss)	2,275	1,176		1,677
Other income and (deductions)
Interest expense, net	(322)	(303)		(298)
Interest expense to affiliates, net	(43)	(53)		(59)
Other, net	(60)	406		355
Total other income and (deductions)	(425)	50		(2)
Income before income taxes	1,850	1,226		1,675
Income taxes	502	207		615
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions	(8)
Net income	1,340	1,019		1,060
Net income (loss) attributable to noncontrolling interests	(32)	184		(10)
Net income attributable to membership interest	1,372	835		1,070
Pension and non-pension postretirement benefit plans:
Unrealized gain (loss) on cash flow hedges, net of taxes	(3)	(132)		(398)
Unrealized gain (loss) on marketable securities, net of taxes	0	(1)		2
Unrealized gain (loss) on equity investments, net of taxes	(3)	8		107
Unrealized gain (loss) on foreign currency translation, net of taxes	(21)	(9)		(10)
Reversal of CENG equity method AOCI, net of taxes	0	(116)		0
Other comprehensive income (loss)	(27)	(250)	[1]	(299)
Comprehensive income	1,313	769		761
Commonwealth Edison Co [Member]
Operating revenues [Abstract]
Revenues	4,905	4,564		4,464
Electric operating revenues	4,901	4,560		4,461
Operating revenues from affiliates	4	4		3
Operating expenses
Rate-regulated utility purchased power and fuel	1,301	1,001		662
Purchased power from affiliate	18	176		512
Operating and maintenance	1,372	1,263		1,211
Operating and maintenance from affiliates	195	166		157
Depreciation and amortization	707	687		669
Taxes other than income	296	293		299
Total operating expenses	3,889	3,586		3,510
Equity in (losses) earnings of unconsolidated affiliates	0	0		0
Gain on sales of assets	1	2		0
Operating Income (Loss)	1,017	980		954
Other income and (deductions)
Interest expense, net	(319)	(308)		(566)
Interest expense to affiliates, net	(13)	(13)		(13)
Other, net	21	17		26
Total other income and (deductions)	(311)	(304)		(553)
Income before income taxes	706	676		401
Income taxes	280	268		152
Net income	426	408		249
Pension and non-pension postretirement benefit plans:
Other comprehensive income (loss)				7,528
Comprehensive income	426	408		249
PECO Energy Co [Member]
Operating revenues [Abstract]
Revenues	3,032	3,094		3,100
Electric Revenue	2,485	2,446		2,499
Gas Domestic Regulated Revenue	545	646		600
Operating revenues from affiliates	2	2		1
Operating expenses
Rate-regulated utility purchased power and fuel	235	327		296
Purchased power	735	740		612
Purchased power from affiliate	220	194		392
Operating and maintenance	684	767		647
Operating and maintenance from affiliates	110	99		101
Depreciation and amortization	260	236		228
Taxes other than income	160	159		158
Total operating expenses	2,404	2,522		2,434
Gain (Loss) on Disposition of Other Assets	2	0		0
Equity in (losses) earnings of unconsolidated affiliates	0	0		0
Operating Income (Loss)	630	572		666
Other income and (deductions)
Interest expense, net	(102)	(101)		(103)
Interest expense to affiliates, net	(12)	(12)		(12)
Other, net	5	7		6
Total other income and (deductions)	(109)	(106)		(109)
Income before income taxes	521	466		557
Income taxes	143	114		162
Net income	378	352		395
Preferred security dividends and redemption	0	0		(7)
Net income attributable to common shareholders	378	352		388
Pension and non-pension postretirement benefit plans:
Comprehensive income	378	352		395
Baltimore Gas and Electric Company [Member]
Operating revenues [Abstract]
Revenues	3,135	3,165		3,065
Electric Revenue	2,490	2,460		2,405
Gas Domestic Regulated Revenue	631	680		647
Operating revenues from affiliates	14	25		13
Operating expenses
Purchased power from affiliate	498	382		452
Utilities Operating Expense, Purchased Power	602	733		676
Utilities Operating Expense, Fuel Used	205	302		293
Operating and maintenance	565	614		551
Operating and maintenance from affiliates	118	103		83
Depreciation and amortization	366	371		348
Taxes other than income	224	221		213
Total operating expenses	2,578	2,726		2,616
Gain (Loss) on Disposition of Other Assets	1	0		0
Equity in (losses) earnings of unconsolidated affiliates	0	0		0
Operating Income (Loss)	558	439		449
Other income and (deductions)
Interest expense, net	(83)	(90)		(106)
Interest expense to affiliates, net	(16)	(16)		(16)
Other, net	18	18		17
Total other income and (deductions)	(81)	(88)		(105)
Income before income taxes	477	351		344
Income taxes	189	140		134
Net income	288	211		210
Preferred security dividends and redemption	(13)	(13)		(13)
Net income attributable to common shareholders	275	198		197
Pension and non-pension postretirement benefit plans:
Comprehensive income	$ 288	$ 211		$ 210

[1] All amounts are net of tax. Amounts in parenthesis represent a decrease in accumulated other comprehensive income.