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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Expenses [Abstract]
Total operating expenses									$ 30,096	$ 32,143	$ 29,619
Operating income (loss)	$ 962	$ 1,353	$ 841	$ 1,218	$ 706	$ 1,144	$ 940	$ 1,099	4,374	3,891	4,388
Other income and (deductions)
Interest expense, net									(1,591)	(1,529)	(1,524)
Other, net									1,227	(112)	947
Total other income and (deductions)									(389)	(1,666)	(613)
Income taxes									774	118	(126)
Net income (loss)									3,028	2,079	3,869
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost									(65)	(66)	(56)
Actuarial loss reclassified to periodic cost, net of tax									149	247	197
Unrealized gain on cash flow hedges									0	12	3
Unrealized gain on marketable securities									0	0	6
Unrealized (loss) gain on foreign currency translation									6	(10)	7
Other comprehensive income (loss)									(198)	42	171
Comprehensive Income									2,737	2,046	3,952
Exelon Corporate [Member]
Operating Expenses [Abstract]
Operating and maintenance									33	(5)	10
Operating and maintenance from affiliates									9	9	25
Other									1	4	4
Total operating expenses									43	8	39
Operating income (loss)									(43)	(8)	(39)
Other income and (deductions)
Interest expense, net									(321)	(312)	(315)
Equity in earnings (losses) of unconsolidated affiliates									3,254	2,183	4,407
Interest income from affiliates, net									39	42	40
Other, net									14	3	1
Total other income and (deductions)									2,986	1,916	4,133
Income before income taxes									2,943	1,908	4,094
Income taxes									7	(97)	315
Net income (loss)									2,936	2,005	3,779
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost									(64)	(66)	(56)
Actuarial loss reclassified to periodic cost, net of tax									148	247	197
Pension and non-pension postretirement benefit plan valuation adjustment									(289)	(143)	10
Unrealized gain on cash flow hedges									1	12	3
Unrealized gain on marketable securities									0	0	6
Unrealized gain (loss) on equity investments									0	1	6
Unrealized (loss) gain on foreign currency translation									0	(10)	7
Other comprehensive income (loss)									(204)	41	173
Comprehensive Income									$ 2,732	$ 2,046	$ 3,952