Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net income (loss)	$ 950	$ 1,460
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	2,741	2,922
Asset impairments	33	9
Gain on sales of assets and businesses	(13)	(33)
Deferred income taxes and amortization of investment tax credits	33	284
Net fair value changes related to derivatives	(194)	107
Net realized and unrealized losses (gains) on NDT funds	196	(404)
Other non-cash operating activities	671	277
Changes in assets and liabilities:
Accounts receivable	1,318	618
Inventories	(14)	19
Accounts payable and accrued expenses	(798)	(924)
Option premiums (paid) received, net	(102)	48
Collateral (posted) received, net	340	(311)
Income taxes	(114)	151
Pension and non-pension postretirement benefit contributions	(558)	(355)
Other assets and liabilities	(1,809)	(970)
Net cash flows provided by operating activities	2,680	2,898
Cash flows from investing activities
Capital expenditures	(3,773)	(3,572)
Proceeds from NDT fund sales	2,488	6,920
Investment in NDT funds	(2,540)	(6,847)
Collection of deferred purchase price	1,102	0
Proceeds from sales of assets and businesses	0	14
Other investing activities	4	26
Net cash flows provided by (used in) investing activities	(2,719)	(3,459)
Cash flows from financing activities
Changes in short-term borrowings	(751)	470
Proceeds from short-term borrowings with maturities greater than 90 days	500	0
Repayments on short-term borrowings with maturities greater than 90 days	0	(125)
Issuance of long-term debt	6,526	850
Retirement of long-term debt	(3,894)	(574)
Dividends paid on common stock	(746)	(704)
Proceeds from employee stock plans	46	75
Other financing activities	(84)	(34)
Net cash flows provided by (used in) financing activities	1,597	(42)
Increase (Decrease) in cash, cash equivalents and restricted cash	1,558	(603)
Cash, cash equivalents and restricted cash at beginning of period	1,122	1,781
Cash, cash equivalents and restricted cash at end of period	2,680	1,178
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(105)	(133)
Increase in deferred purchase price	1,754	0
Increase in PPE related to ARO update	0	301
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income (loss)	368	540
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	1,320	1,580
Asset impairments	18	9
Gain on sales of assets and businesses	(12)	(33)
Deferred income taxes and amortization of investment tax credits	(54)	151
Net fair value changes related to derivatives	(193)	114
Net realized and unrealized losses (gains) on NDT funds	196	(404)
Other non-cash operating activities	136	(50)
Changes in assets and liabilities:
Accounts receivable	1,443	472
Receivables from and payables to affiliates, net	68	(18)
Inventories	(34)	32
Accounts payable and accrued expenses	(666)	(507)
Option premiums (paid) received, net	(102)	48
Collateral (posted) received, net	342	(318)
Income taxes	26	321
Pension and non-pension postretirement benefit contributions	(243)	(158)
Other assets and liabilities	(1,332)	(351)
Net cash flows provided by operating activities	1,281	1,428
Cash flows from investing activities
Capital expenditures	(930)	(890)
Proceeds from NDT fund sales	2,488	6,920
Investment in NDT funds	(2,540)	(6,847)
Collection of deferred purchase price	1,102	0
Proceeds from sales of assets and businesses	0	14
Changes in Exelon/PHI intercompany money pool	0	(179)
Other investing activities	6	8
Net cash flows provided by (used in) investing activities	126	(974)
Cash flows from financing activities
Changes in short-term borrowings	(220)	0
Proceeds from short-term borrowings with maturities greater than 90 days	500	0
Issuance of long-term debt	2,403	40
Retirement of long-term debt	(2,936)	(130)
Changes in Exelon/PHI intercompany money pool	0	(100)
Distributions to member	(937)	(449)
Other financing activities	(30)	(21)
Net cash flows provided by (used in) financing activities	(1,220)	(660)
Increase (Decrease) in cash, cash equivalents and restricted cash	187	(206)
Cash, cash equivalents and restricted cash at beginning of period	449	903
Cash, cash equivalents and restricted cash at end of period	636	697
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(108)	(30)
Increase in deferred purchase price	1,754	0
Increase in PPE related to ARO update	0	301
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income (loss)	107	344
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	547	508
Asset impairments	15	0
Deferred income taxes and amortization of investment tax credits	129	64
Other non-cash operating activities	283	87
Changes in assets and liabilities:
Accounts receivable	(92)	56
Receivables from and payables to affiliates, net	(6)	(16)
Inventories	(7)	(5)
Accounts payable and accrued expenses	4	(121)
Collateral (posted) received, net	(3)	11
Income taxes	(90)	43
Pension and non-pension postretirement benefit contributions	(144)	(68)
Other assets and liabilities	(245)	(236)
Net cash flows provided by operating activities	498	667
Cash flows from investing activities
Capital expenditures	(1,029)	(961)
Other investing activities	(4)	17
Net cash flows provided by (used in) investing activities	(1,033)	(944)
Cash flows from financing activities
Changes in short-term borrowings	(130)	303
Issuance of long-term debt	1,000	400
Retirement of long-term debt	0	(300)
Dividends paid on common stock	(249)	(254)
Contributions from parent	249	124
Other financing activities	(14)	(10)
Net cash flows provided by (used in) financing activities	856	263
Increase (Decrease) in cash, cash equivalents and restricted cash	321	(14)
Cash, cash equivalents and restricted cash at beginning of period	403	330
Cash, cash equivalents and restricted cash at end of period	724	316
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	18	(77)
PECO Energy Co [Member]
Cash flows from operating activities
Net income (loss)	178	270
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	173	164
Deferred income taxes and amortization of investment tax credits	6	8
Other non-cash operating activities	25	15
Changes in assets and liabilities:
Accounts receivable	22	39
Receivables from and payables to affiliates, net	3	(4)
Inventories	10	12
Accounts payable and accrued expenses	27	(31)
Income taxes	15	(11)
Pension and non-pension postretirement benefit contributions	(18)	(27)
Other assets and liabilities	(48)	(117)
Net cash flows provided by operating activities	393	318
Cash flows from investing activities
Capital expenditures	(512)	(447)
Changes in Exelon/PHI intercompany money pool	68	0
Other investing activities	3	4
Net cash flows provided by (used in) investing activities	(441)	(443)
Cash flows from financing activities
Issuance of long-term debt	350	0
Changes in Exelon/PHI intercompany money pool	0	52
Dividends paid on common stock	(170)	(180)
Contributions from parent	231	145
Other financing activities	(3)	(1)
Net cash flows provided by (used in) financing activities	408	16
Increase (Decrease) in cash, cash equivalents and restricted cash	360	(109)
Cash, cash equivalents and restricted cash at beginning of period	27	135
Cash, cash equivalents and restricted cash at end of period	387	26
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	42	33
Baltimore Gas and Electric Company [Member]
Cash flows from operating activities
Net income (loss)	219	206
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	272	252
Deferred income taxes and amortization of investment tax credits	22	47
Other non-cash operating activities	50	41
Changes in assets and liabilities:
Accounts receivable	19	85
Receivables from and payables to affiliates, net	(26)	(14)
Inventories	10	5
Accounts payable and accrued expenses	(15)	(73)
Collateral (posted) received, net	0	(5)
Income taxes	26	(29)
Pension and non-pension postretirement benefit contributions	(68)	(42)
Other assets and liabilities	(5)	(21)
Net cash flows provided by operating activities	504	452
Cash flows from investing activities
Capital expenditures	(548)	(542)
Other investing activities	(4)	4
Net cash flows provided by (used in) investing activities	(552)	(538)
Cash flows from financing activities
Changes in short-term borrowings	(76)	194
Issuance of long-term debt	400	0
Dividends paid on common stock	(123)	(112)
Contributions from parent	26	0
Other financing activities	(8)	0
Net cash flows provided by (used in) financing activities	219	82
Increase (Decrease) in cash, cash equivalents and restricted cash	171	(4)
Cash, cash equivalents and restricted cash at beginning of period	25	13
Cash, cash equivalents and restricted cash at end of period	196	9
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(14)	24
Pepco Holdings LLC [Member]
Cash flows from operating activities
Net income (loss)	202	223
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	385	369
Deferred income taxes and amortization of investment tax credits	(74)	2
Other non-cash operating activities	107	54
Changes in assets and liabilities:
Accounts receivable	(64)	(34)
Receivables from and payables to affiliates, net	(22)	(8)
Inventories	6	(25)
Accounts payable and accrued expenses	14	(25)
Income taxes	(30)	(12)
Pension and non-pension postretirement benefit contributions	(31)	(11)
Other assets and liabilities	(146)	(114)
Net cash flows provided by operating activities	347	419
Cash flows from investing activities
Capital expenditures	(686)	(698)
Other investing activities	2	2
Net cash flows provided by (used in) investing activities	(684)	(696)
Cash flows from financing activities
Changes in short-term borrowings	(189)	(27)
Repayments on short-term borrowings with maturities greater than 90 days	0	(125)
Issuance of long-term debt	373	410
Retirement of long-term debt	(35)	(125)
Changes in Exelon/PHI intercompany money pool	10	3
Distributions to member	(268)	(216)
Contributions from member	359	283
Other financing activities	(8)	(4)
Net cash flows provided by (used in) financing activities	242	199
Increase (Decrease) in cash, cash equivalents and restricted cash	(95)	(78)
Cash, cash equivalents and restricted cash at beginning of period	181	186
Cash, cash equivalents and restricted cash at end of period	86	108
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(24)	(74)
Potomac Electric Power Company [Member]
Cash flows from operating activities
Net income (loss)	109	119
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	186	186
Deferred income taxes and amortization of investment tax credits	(22)	10
Other non-cash operating activities	11	8
Changes in assets and liabilities:
Accounts receivable	(45)	(36)
Receivables from and payables to affiliates, net	(22)	4
Inventories	3	(20)
Accounts payable and accrued expenses	11	(25)
Income taxes	(18)	(23)
Pension and non-pension postretirement benefit contributions	(6)	(6)
Other assets and liabilities	(52)	(40)
Net cash flows provided by operating activities	155	177
Cash flows from investing activities
Capital expenditures	(324)	(298)
Changes in Exelon/PHI intercompany money pool	0	(38)
Other investing activities	(3)	1
Net cash flows provided by (used in) investing activities	(327)	(335)
Cash flows from financing activities
Changes in short-term borrowings	(68)	(40)
Issuance of long-term debt	150	260
Retirement of long-term debt	(1)	(117)
Changes in Exelon/PHI intercompany money pool	50	0
Dividends paid on common stock	(101)	(72)
Contributions from parent	137	129
Other financing activities	(6)	(3)
Net cash flows provided by (used in) financing activities	161	157
Increase (Decrease) in cash, cash equivalents and restricted cash	(11)	(1)
Cash, cash equivalents and restricted cash at beginning of period	63	53
Cash, cash equivalents and restricted cash at end of period	52	52
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(28)	(18)
Delmarva Power and Light Company [Member]
Cash flows from operating activities
Net income (loss)	64	83
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	94	91
Deferred income taxes and amortization of investment tax credits	(19)	(5)
Other non-cash operating activities	40	11
Changes in assets and liabilities:
Accounts receivable	6	15
Receivables from and payables to affiliates, net	(2)	(11)
Inventories	0	(3)
Accounts payable and accrued expenses	3	6
Income taxes	(12)	11
Pension and non-pension postretirement benefit contributions	0	(1)
Other assets and liabilities	(21)	(26)
Net cash flows provided by operating activities	153	171
Cash flows from investing activities
Capital expenditures	(184)	(160)
Changes in Exelon/PHI intercompany money pool	(55)	0
Other investing activities	(3)	1
Net cash flows provided by (used in) investing activities	(242)	(159)
Cash flows from financing activities
Changes in short-term borrowings	(56)	0
Issuance of long-term debt	100	0
Retirement of long-term debt	(1)	0
Changes in Exelon/PHI intercompany money pool	0	38
Dividends paid on common stock	(66)	(70)
Contributions from parent	106	0
Other financing activities	(1)	0
Net cash flows provided by (used in) financing activities	82	(32)
Increase (Decrease) in cash, cash equivalents and restricted cash	(7)	(20)
Cash, cash equivalents and restricted cash at beginning of period	13	24
Cash, cash equivalents and restricted cash at end of period	6	4
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(4)	(17)
Atlantic City Electric Company [Member]
Cash flows from operating activities
Net income (loss)	31	24
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	86	71
Deferred income taxes and amortization of investment tax credits	(30)	2
Other non-cash operating activities	34	7
Changes in assets and liabilities:
Accounts receivable	(23)	(11)
Receivables from and payables to affiliates, net	9	(9)
Inventories	2	(1)
Accounts payable and accrued expenses	17	16
Income taxes	2	6
Pension and non-pension postretirement benefit contributions	(2)	0
Other assets and liabilities	(68)	(44)
Net cash flows provided by operating activities	58	61
Cash flows from investing activities
Capital expenditures	(178)	(227)
Other investing activities	5	0
Net cash flows provided by (used in) investing activities	(173)	(227)
Cash flows from financing activities
Changes in short-term borrowings	(65)	13
Repayments on short-term borrowings with maturities greater than 90 days	0	(125)
Issuance of long-term debt	123	150
Retirement of long-term debt	(34)	(9)
Changes in Exelon/PHI intercompany money pool	5	0
Dividends paid on common stock	(35)	(24)
Contributions from parent	116	155
Other financing activities	(1)	(1)
Net cash flows provided by (used in) financing activities	109	159
Increase (Decrease) in cash, cash equivalents and restricted cash	(6)	(7)
Cash, cash equivalents and restricted cash at beginning of period	28	30
Cash, cash equivalents and restricted cash at end of period	22	23
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	$ 7	$ (35)