Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net income	$ 2,220	$ 1,979
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	4,393	4,511
Asset impairments	174	49
Gain on sales of assets and businesses	(15)	(55)
Deferred income taxes and amortization of investment tax credits	412	97
Net fair value changes related to derivatives	96	67
Net realized and unrealized gains on NDT funds	(467)	(21)
Other non-cash operating activities	460	804
Changes in assets and liabilities:
Accounts receivable	445	(167)
Inventories	(94)	(24)
Accounts payable and accrued expenses	(671)	84
Option premiums received (paid), net	13	(36)
Collateral (posted) received, net	(254)	222
Income taxes	143	166
Pension and non-pension postretirement benefit contributions	(377)	(362)
Other assets and liabilities	(1,079)	(639)
Net cash flows provided by operating activities	5,399	6,675
Cash flows from investing activities
Capital expenditures	(5,259)	(5,497)
Proceeds from NDT fund sales	8,443	6,379
Investment in NDT funds	(8,437)	(6,553)
Acquisition of assets and businesses, net	0	(57)
Proceeds from sales of assets and businesses	17	90
Other investing activities	21	29
Net cash flows used in investing activities	(5,215)	(5,609)
Cash flows from financing activities
Changes in short-term borrowings	430	(218)
Proceeds from short-term borrowings with maturities greater than 90 days	0	126
Repayments on short-term borrowings with maturities greater than 90 days	(125)	(1)
Issuance of long-term debt	1,576	2,664
Retirement of long-term debt	(644)	(1,480)
Dividends paid on common stock	(1,055)	(999)
Proceeds from employee stock plans	94	67
Other financing activities	(63)	(94)
Net cash flows provided by (used in) financing activities	213	65
Increase (Decrease) in cash, cash equivalents and restricted cash	397	1,131
Cash, cash equivalents and restricted cash at beginning of period	1,781	1,190
Cash, cash equivalents and restricted cash at end of period	2,178	2,321
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(96)	(175)
Increase in PPE related to ARO update	344	67
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income	784	667
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	2,377	2,608
Asset impairments	174	49
Gain on sales of assets and businesses	(15)	(48)
Deferred income taxes and amortization of investment tax credits	201	(278)
Net fair value changes related to derivatives	102	73
Net realized and unrealized gains on NDT funds	(467)	(21)
Other non-cash operating activities	(95)	187
Changes in assets and liabilities:
Accounts receivable	395	126
Receivables from and payables to affiliates, net	(12)	(7)
Inventories	(36)	(10)
Accounts payable and accrued expenses	(428)	(59)
Option premiums received (paid), net	13	(36)
Collateral (posted) received, net	(292)	228
Income taxes	327	220
Pension and non-pension postretirement benefit contributions	(165)	(134)
Other assets and liabilities	(390)	(154)
Net cash flows provided by operating activities	2,473	3,411
Cash flows from investing activities
Capital expenditures	(1,282)	(1,660)
Proceeds from NDT fund sales	8,443	6,379
Investment in NDT funds	(8,437)	(6,553)
Acquisition of assets and businesses, net	0	(57)
Proceeds from sales of assets and businesses	17	90
Other investing activities	(6)	(5)
Net cash flows used in investing activities	(1,265)	(1,806)
Cash flows from financing activities
Issuance of long-term debt	41	14
Retirement of long-term debt	(196)	(100)
Changes in Exelon/PHI intercompany money pool	(100)	(54)
Distributions to member	(674)	(688)
Contributions from member	0	54
Other financing activities	(37)	(46)
Net cash flows provided by (used in) financing activities	(966)	(820)
Increase (Decrease) in cash, cash equivalents and restricted cash	242	785
Cash, cash equivalents and restricted cash at beginning of period	903	554
Cash, cash equivalents and restricted cash at end of period	1,145	1,339
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(24)	(226)
Increase in PPE related to ARO update	342	47
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income	544	523
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	767	696
Deferred income taxes and amortization of investment tax credits	115	214
Other non-cash operating activities	180	187
Changes in assets and liabilities:
Accounts receivable	(38)	(190)
Receivables from and payables to affiliates, net	(27)	8
Inventories	(16)	4
Accounts payable and accrued expenses	(132)	(38)
Collateral (posted) received, net	43	(10)
Income taxes	25	(65)
Pension and non-pension postretirement benefit contributions	(71)	(41)
Other assets and liabilities	(245)	(170)
Net cash flows provided by operating activities	1,145	1,118
Cash flows from investing activities
Capital expenditures	(1,413)	(1,540)
Other investing activities	25	22
Net cash flows used in investing activities	(1,388)	(1,518)
Cash flows from financing activities
Changes in short-term borrowings	387	0
Issuance of long-term debt	400	1,350
Retirement of long-term debt	(300)	(840)
Contributions from parent	187	387
Dividends paid on common stock	(380)	(345)
Other financing activities	(10)	(16)
Net cash flows provided by (used in) financing activities	284	536
Increase (Decrease) in cash, cash equivalents and restricted cash	41	136
Cash, cash equivalents and restricted cash at beginning of period	330	144
Cash, cash equivalents and restricted cash at end of period	371	280
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(52)	(28)
PECO Energy Co [Member]
Cash flows from operating activities
Net income	410	336
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	247	224
Gain on sales of assets and businesses	0	(1)
Deferred income taxes and amortization of investment tax credits	6	5
Other non-cash operating activities	28	41
Changes in assets and liabilities:
Accounts receivable	46	(85)
Receivables from and payables to affiliates, net	(12)	1
Inventories	(3)	(13)
Accounts payable and accrued expenses	(32)	(1)
Income taxes	(15)	(16)
Pension and non-pension postretirement benefit contributions	(26)	(25)
Other assets and liabilities	(111)	26
Net cash flows provided by operating activities	538	492
Cash flows from investing activities
Capital expenditures	(675)	(615)
Other investing activities	7	6
Net cash flows used in investing activities	(668)	(609)
Cash flows from financing activities
Issuance of long-term debt	325	700
Retirement of long-term debt	0	(500)
Contributions from parent	174	71
Dividends paid on common stock	(268)	(300)
Other financing activities	(6)	(22)
Net cash flows provided by (used in) financing activities	225	(51)
Increase (Decrease) in cash, cash equivalents and restricted cash	95	(168)
Cash, cash equivalents and restricted cash at beginning of period	135	275
Cash, cash equivalents and restricted cash at end of period	230	107
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	42	4
Baltimore Gas and Electric Company [Member]
Cash flows from operating activities
Net income	261	242
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	368	358
Deferred income taxes and amortization of investment tax credits	66	82
Other non-cash operating activities	63	42
Changes in assets and liabilities:
Accounts receivable	110	72
Receivables from and payables to affiliates, net	(14)	(4)
Inventories	(5)	(8)
Accounts payable and accrued expenses	(28)	(3)
Collateral (posted) received, net	(5)	1
Income taxes	(43)	(48)
Pension and non-pension postretirement benefit contributions	(45)	(50)
Other assets and liabilities	(65)	(9)
Net cash flows provided by operating activities	663	675
Cash flows from investing activities
Capital expenditures	(842)	(667)
Other investing activities	4	8
Net cash flows used in investing activities	(838)	(659)
Cash flows from financing activities
Changes in short-term borrowings	(35)	(77)
Issuance of long-term debt	400	300
Contributions from parent	104	18
Dividends paid on common stock	(169)	(157)
Other financing activities	(7)	(2)
Net cash flows provided by (used in) financing activities	293	82
Increase (Decrease) in cash, cash equivalents and restricted cash	118	98
Cash, cash equivalents and restricted cash at beginning of period	13	18
Cash, cash equivalents and restricted cash at end of period	131	116
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	6	44
Pepco Holdings LLC [Member]
Cash flows from operating activities
Net income	412	336
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	562	555
Deferred income taxes and amortization of investment tax credits	8	50
Other non-cash operating activities	122	109
Changes in assets and liabilities:
Accounts receivable	(64)	(89)
Receivables from and payables to affiliates, net	1	10
Inventories	(36)	0
Accounts payable and accrued expenses	0	115
Income taxes	(11)	(31)
Pension and non-pension postretirement benefit contributions	(15)	(66)
Other assets and liabilities	(102)	(144)
Net cash flows provided by operating activities	877	845
Cash flows from investing activities
Capital expenditures	(1,006)	(988)
Other investing activities	3	2
Net cash flows used in investing activities	(1,003)	(986)
Cash flows from financing activities
Changes in short-term borrowings	78	(141)
Proceeds from short-term borrowings with maturities greater than 90 days	0	125
Repayments on short-term borrowings with maturities greater than 90 days	(125)	0
Issuance of long-term debt	410	300
Retirement of long-term debt	(130)	(33)
Changes in Exelon/PHI intercompany money pool	10	10
Distributions to member	(429)	(232)
Contributions from member	283	237
Other financing activities	(5)	(6)
Net cash flows provided by (used in) financing activities	92	260
Increase (Decrease) in cash, cash equivalents and restricted cash	(34)	119
Cash, cash equivalents and restricted cash at beginning of period	186	95
Cash, cash equivalents and restricted cash at end of period	152	214
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(62)	54
Potomac Electric Power Company [Member]
Cash flows from operating activities
Net income	217	174
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	281	286
Deferred income taxes and amortization of investment tax credits	12	(5)
Other non-cash operating activities	43	42
Changes in assets and liabilities:
Accounts receivable	(49)	(36)
Receivables from and payables to affiliates, net	4	(9)
Inventories	(23)	6
Accounts payable and accrued expenses	(12)	104
Income taxes	(23)	(18)
Pension and non-pension postretirement benefit contributions	(10)	(11)
Other assets and liabilities	(55)	(137)
Net cash flows provided by operating activities	385	396
Cash flows from investing activities
Capital expenditures	(455)	(475)
Other investing activities	2	3
Net cash flows used in investing activities	(453)	(472)
Cash flows from financing activities
Changes in short-term borrowings	(28)	38
Issuance of long-term debt	260	100
Retirement of long-term debt	(118)	(8)
Contributions from parent	129	85
Dividends paid on common stock	(173)	(128)
Other financing activities	(3)	(4)
Net cash flows provided by (used in) financing activities	67	83
Increase (Decrease) in cash, cash equivalents and restricted cash	(1)	7
Cash, cash equivalents and restricted cash at beginning of period	53	40
Cash, cash equivalents and restricted cash at end of period	52	47
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(7)	15
Delmarva Power and Light Company [Member]
Cash flows from operating activities
Net income	116	90
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	138	135
Deferred income taxes and amortization of investment tax credits	(2)	24
Other non-cash operating activities	21	16
Changes in assets and liabilities:
Accounts receivable	29	13
Receivables from and payables to affiliates, net	(7)	(14)
Inventories	(7)	(3)
Accounts payable and accrued expenses	3	18
Income taxes	11	0
Pension and non-pension postretirement benefit contributions	(1)	0
Other assets and liabilities	(22)	13
Net cash flows provided by operating activities	279	292
Cash flows from investing activities
Capital expenditures	(245)	(254)
Other investing activities	1	1
Net cash flows used in investing activities	(244)	(253)
Cash flows from financing activities
Changes in short-term borrowings	57	(216)
Issuance of long-term debt	0	200
Retirement of long-term debt	0	(4)
Contributions from parent	0	150
Dividends paid on common stock	(105)	(58)
Other financing activities	0	(3)
Net cash flows provided by (used in) financing activities	(48)	69
Increase (Decrease) in cash, cash equivalents and restricted cash	(13)	108
Cash, cash equivalents and restricted cash at beginning of period	24	2
Cash, cash equivalents and restricted cash at end of period	11	110
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	(13)	20
Atlantic City Electric Company [Member]
Cash flows from operating activities
Net income	87	76
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion, including nuclear fuel and energy contract amortization	114	107
Deferred income taxes and amortization of investment tax credits	2	24
Other non-cash operating activities	21	24
Changes in assets and liabilities:
Accounts receivable	(44)	(66)
Receivables from and payables to affiliates, net	(4)	(3)
Inventories	(4)	(2)
Accounts payable and accrued expenses	27	21
Income taxes	5	(3)
Pension and non-pension postretirement benefit contributions	0	(6)
Other assets and liabilities	(18)	(12)
Net cash flows provided by operating activities	186	160
Cash flows from investing activities
Capital expenditures	(300)	(247)
Other investing activities	0	(1)
Net cash flows used in investing activities	(300)	(248)
Cash flows from financing activities
Changes in short-term borrowings	49	37
Proceeds from short-term borrowings with maturities greater than 90 days	0	125
Repayments on short-term borrowings with maturities greater than 90 days	(125)	0
Issuance of long-term debt	150	0
Retirement of long-term debt	(13)	(22)
Contributions from parent	155	0
Dividends paid on common stock	(100)	(46)
Other financing activities	(1)	0
Net cash flows provided by (used in) financing activities	115	94
Increase (Decrease) in cash, cash equivalents and restricted cash	1	6
Cash, cash equivalents and restricted cash at beginning of period	30	31
Cash, cash equivalents and restricted cash at end of period	31	37
Supplemental Cash Flow Information
Increase (decrease) in capital expenditures not paid	$ (37)	$ 16