Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Condensed Statements of Operations and Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Expenses [Abstract]
Total operating expenses										$ 32,143	$ 29,619	$ 28,106
Operating income (loss)		$ 708	$ 1,146	$ 942	$ 1,101	$ 1,288	$ 1,499	$ 300	$ 1,308	3,898	4,395	3,212
Other income and (deductions)
Interest expense, net										(1,529)	(1,524)	(1,495)
Equity in earnings (losses) of unconsolidated affiliates										(28)	(32)	(24)
Other, net										(112)	947	297
Total other income and (deductions)										(1,666)	(613)	(1,239)
Income taxes		$ 26								120	(126)	753
Net income (loss)										2,084	3,876	1,196
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost										(66)	(56)	(48)
Actuarial loss reclassified to periodic cost, net of tax										247	197	184
Unrealized gain on cash flow hedges										12	3	2
Unrealized gain on marketable securities										0	6	1
Unrealized (loss) gain on foreign currency translation										(10)	7	10
Other comprehensive income (loss)										42	171	(36)
Comprehensive Income										2,051	3,959	1,085
Exelon Corporate [Member]
Operating Expenses [Abstract]
Operating and maintenance										(5)	10	221
Operating and maintenance from affiliates	[1]									9	25	51
Other										4	4	4
Total operating expenses										8	39	276
Operating income (loss)										(8)	(39)	(276)
Other income and (deductions)
Interest expense, net										(312)	(315)	(312)
Equity in earnings (losses) of unconsolidated affiliates										2,188	4,414	1,508
Interest income from affiliates, net										42	40	39
Other, net										3	1	7
Total other income and (deductions)										1,921	4,140	1,242
Income before income taxes										1,913	4,101	966
Income taxes										(97)	315	(155)
Net income (loss)										2,010	3,786	1,121
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost										(66)	(56)	(48)
Actuarial loss reclassified to periodic cost, net of tax										247	197	184
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax										(143)	10	(181)
Unrealized gain on cash flow hedges										12	3	2
Unrealized gain (loss) on equity investments										1	6	(4)
Unrealized gain on marketable securities										0	6	1
Unrealized (loss) gain on foreign currency translation										(10)	7	10
Other comprehensive income (loss)										41	173	(36)
Comprehensive Income										$ 2,051	$ 3,959	$ 1,085

[1] Exelon Corporate receives a variety of corporate support services from BSC, including legal, human resources, financial, information technology and supply management services. All services are provided at cost, including applicable overhead.