Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net income	$ 1,204	$ 2,250	$ 1,820
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	5,576	3,987	3,868
Impairments of long-lived assets	306	36	687
Gain on consolidation and acquisition of businesses	0	0	(296)
(Gain) Loss on sales of assets	48	(18)	(437)
Deferred income taxes and amortization of investment tax credits	664	752	502
Net fair value changes related to derivatives	24	(367)	716
Net realized and unrealized (gains) losses on nuclear decommissioning trust fund investments	(229)	131	(210)
Other non-cash operating activities	1,333	1,109	1,054
Changes in assets and liabilities:
Accounts receivable	(432)	240	(318)
Inventories	7	4	(380)
Accounts payable and accrued expenses	771	(121)	49
Increase (Decrease) in Premiums Receivable	66	(58)	(38)
Increase (Decrease) Cash Collateral from Counterparties	931	347	(1,719)
Income taxes	576	97	(143)
Pension and non-pension postretirement benefit contributions	(397)	(502)	(617)
Increase (Decrease) in Prepaid Taxes	(1,250)	0	0
Other assets and liabilities	(621)	(387)	(157)
Net cash flows provided by operating activities	8,445	7,616	4,457
Cash flows from investing activities
Capital expenditures	(8,553)	(7,624)	(6,077)
Proceeds from Sale and Collection of Lease Receivables	360	0	335
Proceeds from nuclear decommissioning trust fund sales	9,496	6,895	7,396
Investment in nuclear decommissioning trust funds	(9,738)	(7,147)	(7,551)
Acquisitions of businesses, net	(6,934)	(40)	(386)
Proceeds from sales of long-lived assets	61	147	1,719
Proceeds from sales of investments	0	0	7
Cash and restricted cash acquired from consolidations and acquisitions	0	0	140
Purchases of investments	0	0	(3)
Change in restricted cash	(42)	66	(104)
Distribution from CENG	0	0	13
Other investing activities	(153)	(119)	(88)
Net cash flows used in investing activities	(15,503)	(7,822)	(4,599)
Cash flows from financing activities
Repayments of Debt, Maturing in More than Three Months	(462)	0	0
Issuance of long-term debt	4,716	6,709	3,463
Retirement of long-term debt	(1,936)	(2,687)	(1,545)
Redemption of preference stock	(190)	0	0
Distribution to noncontrolling interest of consolidated VIE	0	0	(421)
Dividends paid on common stock	(1,166)	(1,105)	(1,065)
Proceeds from employee stock plans	(55)	(32)	(35)
Other financing activities	(85)	(99)	(178)
Proceeds from Noncontrolling Interests	372	32	0
Proceeds from (Repayments of) Short-term Debt	(353)	80	122
Proceeds from Issuance of Common Stock	0	1,868	0
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	240	0	0
Net cash flows provided by financing activities	1,191	4,830	411
(Decrease) Increase in cash and cash equivalents	(5,867)	4,624	269
Cash and cash equivalents at beginning of period	6,502	1,878	1,609
Cash and cash equivalents at end of period	635	6,502	1,878
Predecessor [Member]
Adjustments to reconcile net income to net cash flows provided by operating activities:
Impairments of long-lived assets		0
(Gain) Loss on sales of assets			0
Parent Company [Member]
Cash flows from operating activities
Net income	1,134	2,269	1,623
Adjustments to reconcile net income to net cash flows provided by operating activities:
Increase (Decrease) Due from Affiliates	1,390	(1,217)	(83)
Changes in assets and liabilities:
Net cash flows provided by operating activities	1,029	3,071	806
Cash flows from investing activities
Capital expenditures	0	0	1
Payments to Acquire Businesses, Net of Cash Acquired	6,962
Proceeds from Sale and Collection of Lease Receivables	0	0	335
Other investing activities	5	(55)	(126)
Net cash flows used in investing activities	(7,324)	(934)	57
Cash flows from financing activities
Issuance of long-term debt	1,800	4,200	1,150
Retirement of long-term debt	(46)	(2,263)	(23)
Dividends paid on common stock	(1,166)	(1,105)	(1,065)
Proceeds from employee stock plans	(55)	(32)	(35)
Other financing activities	(20)	(58)	(84)
Contribution from member	1,912	3,209	1,370
Proceeds from Issuance of Common Stock	0	1,868	0
Net cash flows provided by financing activities	623	2,674	13
(Decrease) Increase in cash and cash equivalents	(5,672)	4,811	876
Cash and cash equivalents at beginning of period	5,690	879	3
Cash and cash equivalents at end of period	18	5,690	879
Increase (Decrease) Due from Affiliates	1,390	(1,217)	(83)
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income	558	1,340	1,019
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	3,519	2,589	2,519
Impairments of long-lived assets	243	12	663
Gain on consolidation and acquisition of businesses	0	0	(296)
(Gain) Loss on sales of assets	59	(12)	(437)
Deferred income taxes and amortization of investment tax credits	(269)	49	(198)
Net fair value changes related to derivatives	40	(249)	635
Net realized and unrealized (gains) losses on nuclear decommissioning trust fund investments	(229)	131	(210)
Other non-cash operating activities	15	268	346
Increase (Decrease) Due from Affiliates	0	0	44
Changes in assets and liabilities:
Accounts receivable	(152)	194	(215)
Receivables from and payables to affiliates, net	(21)	15	15
Inventories	(4)	16	(359)
Accounts payable and accrued expenses	29	(149)	29
Increase (Decrease) in Premiums Receivable	66	(58)	(38)
Increase (Decrease) Cash Collateral from Counterparties	923	407	(1,748)
Income taxes	182	(18)	265
Pension and non-pension postretirement benefit contributions	(152)	(245)	(297)
Other assets and liabilities	(231)	(207)	57
Net cash flows provided by operating activities	4,444	4,199	1,826
Cash flows from investing activities
Capital expenditures	(3,078)	(3,841)	(3,012)
Proceeds from nuclear decommissioning trust fund sales	9,496	6,895	7,396
Investment in nuclear decommissioning trust funds	(9,738)	(7,147)	(7,551)
Acquisitions of businesses, net	(293)	(40)	(386)
Proceeds from sales of long-lived assets	37	147	1,719
Cash and restricted cash acquired from consolidations and acquisitions	0	0	140
Change in restricted cash	(35)	35	(87)
Distribution from CENG	0	0	13
Other investing activities	(240)	(118)	(43)
Net cash flows used in investing activities	(3,851)	(4,069)	(1,767)
Cash flows from financing activities
Repayments of Debt, Maturing in More than Three Months	(162)	0	0
Issuance of long-term debt	388	1,309	1,112
Retirement of long-term debt	(202)	(89)	(586)
Repayments of Related Party Debt	0	(550)	0
Increase (Decrease) in Due to Affiliates	(1,191)	1,252	0
Distribution to noncontrolling interest of consolidated VIE	0	0	(421)
Other financing activities	(19)	(6)	(67)
Distribution to member	(922)	(2,474)	(645)
Contribution from member	142	47	53
Proceeds from Noncontrolling Interests	372	32	0
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	620	0	17
Proceeds from Debt, Maturing in More than Three Months	240	0	0
Net cash flows provided by financing activities	(734)	(479)	(537)
(Decrease) Increase in cash and cash equivalents	(141)	(349)	(478)
Cash and cash equivalents at beginning of period	431	780	1,258
Cash and cash equivalents at end of period	290	431	780
Increase (Decrease) Due from Affiliates	0	0	44
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income	378	426	408
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	775	707	687
Deferred income taxes and amortization of investment tax credits	439	353	433
Other non-cash operating activities	215	416	255
Changes in assets and liabilities:
Accounts receivable	(25)	(93)	(121)
Receivables from and payables to affiliates, net	3	(19)	(11)
Inventories	1	(40)	(16)
Accounts payable and accrued expenses	339	68	95
Increase (Decrease) Cash Collateral from Counterparties	7	(33)	2
Income taxes	306	192	(159)
Pension and non-pension postretirement benefit contributions	(38)	(150)	(248)
Other assets and liabilities	105	69	1
Net cash flows provided by operating activities	2,505	1,896	1,326
Cash flows from investing activities
Capital expenditures	(2,734)	(2,398)	(1,689)
Proceeds from sales of investments	0	0	7
Purchases of investments	0	0	(3)
Change in restricted cash	0	2	(2)
Other investing activities	49	34	32
Net cash flows used in investing activities	(2,685)	(2,362)	(1,655)
Cash flows from financing activities
Issuance of long-term debt	1,200	850	900
Retirement of long-term debt	(665)	(260)	(617)
Dividends paid on common stock	(369)	(299)	(307)
Other financing activities	(18)	(16)	(10)
Contributions from parent	315	202	273
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	(294)	(10)	120
Net cash flows provided by financing activities	169	467	359
(Decrease) Increase in cash and cash equivalents	(11)	1	30
Cash and cash equivalents at beginning of period	67	66	36
Cash and cash equivalents at end of period	56	67	66
PECO Energy Co [Member]
Cash flows from operating activities
Net income	438	378	352
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	270	260	236
Deferred income taxes and amortization of investment tax credits	78	90	88
Other non-cash operating activities	65	70	92
Increase (Decrease) Due from Affiliates	(131)	0	0
Changes in assets and liabilities:
Accounts receivable	(71)	37	(16)
Receivables from and payables to affiliates, net	6	3	(6)
Inventories	6	10	2
Accounts payable and accrued expenses	67	(25)	58
Income taxes	8	(9)	(57)
Pension and non-pension postretirement benefit contributions	(30)	(40)	(16)
Other assets and liabilities	(8)	(4)	(21)
Net cash flows provided by operating activities	829	770	712
Cash flows from investing activities
Capital expenditures	(686)	(601)	(661)
Change in restricted cash	(1)	(1)	0
Other investing activities	20	14	12
Net cash flows used in investing activities	(798)	(588)	(649)
Cash flows from financing activities
Issuance of long-term debt	300	350	300
Retirement of long-term debt	(300)	0	(250)
Dividends paid on common stock	(277)	(279)	(320)
Other financing activities	(4)	(4)	(4)
Contributions from parent	18	16	24
Net cash flows provided by financing activities	(263)	83	(250)
(Decrease) Increase in cash and cash equivalents	(232)	265	(187)
Cash and cash equivalents at beginning of period	295	30	217
Cash and cash equivalents at end of period	63	295	30
Increase (Decrease) Due from Affiliates	(131)	0	0
Baltimore Gas and Electric Company [Member]
Cash flows from operating activities
Net income	294	288	211
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	423	366	371
Impairments of long-lived assets	52	0	0
Deferred income taxes and amortization of investment tax credits	118	165	116
Other non-cash operating activities	88	137	180
Changes in assets and liabilities:
Accounts receivable	(98)	84	46
Receivables from and payables to affiliates, net	3	(2)	(1)
Inventories	1	18	(6)
Accounts payable and accrued expenses	138	(3)	(75)
Increase (Decrease) Cash Collateral from Counterparties	0	(27)	27
Income taxes	18	(54)	45
Pension and non-pension postretirement benefit contributions	(49)	(17)	(16)
Other assets and liabilities	(43)	(173)	(158)
Net cash flows provided by operating activities	945	782	740
Cash flows from investing activities
Capital expenditures	(934)	(719)	(620)
Change in restricted cash	0	26	(22)
Other investing activities	24	18	20
Net cash flows used in investing activities	(910)	(675)	(622)
Cash flows from financing activities
Issuance of long-term debt	850	0	0
Retirement of long-term debt	(379)	(75)	(70)
Redemption of preference stock	(190)	0	0
Preferred Stock, Redemption Amount	190
Dividends paid on common stock	(179)	(158)	0
Other financing activities	(11)	(13)	13
Contributions from parent	61	7	0
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	(165)	90	(15)
Dividends paid on preferred securities	(8)	(13)	(13)
Net cash flows provided by financing activities	(21)	(162)	(85)
(Decrease) Increase in cash and cash equivalents	14	(55)	33
Cash and cash equivalents at beginning of period	9	64	31
Cash and cash equivalents at end of period	23	9	64
Pepco Holdings LLC [Member] | Predecessor [Member]
Cash flows from operating activities
Net income		327	242
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		(9)	0
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization		624	526
Impairments of long-lived assets			81
(Gain) Loss on sales of assets		(46)
Deferred income taxes and amortization of investment tax credits		134	303
Net fair value changes related to derivatives		0	0
Other non-cash operating activities		167	127
Changes in assets and liabilities:
Accounts receivable		(105)	(2)
Receivables from and payables to affiliates, net		0	0
Inventories		0	8
Accounts payable and accrued expenses		(41)	(31)
Increase (Decrease) Cash Collateral from Counterparties		0	1
Income taxes		8	(197)
Pension and non-pension postretirement benefit contributions		(21)	(18)
Other assets and liabilities		(99)	(186)
Net cash flows provided by operating activities		939	854
Cash flows from investing activities
Capital expenditures		(1,230)	(1,223)
Proceeds from sales of long-lived assets		54	0
Purchases of investments		0	0
Change in restricted cash		6	(12)
Other investing activities		9	9
Net cash flows used in investing activities		(1,161)	(1,226)
Cash flows from financing activities
Repayments of Debt, Maturing in More than Three Months		0	0
Issuance of long-term debt		558	766
Retirement of long-term debt		(430)	(462)
Increase (Decrease) in Due to Affiliates		0	0
Dividends paid on common stock		(275)	(272)
Proceeds from employee stock plans		(18)	(33)
Other financing activities		(26)	(11)
Distribution to member		0	0
Proceeds from (Repayments of) Short-term Debt		34	183
Proceeds from Issuance of Preferred Stock and Preference Stock		54	126
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less		300	0
Net cash flows provided by financing activities		233	363
(Decrease) Increase in cash and cash equivalents		11	(9)
Cash and cash equivalents at beginning of period	26	15	24
Cash and cash equivalents at end of period		26	15
Proceeds from Issuance of Preferred Stock and Preference Stock		54	126
Pepco Holdings LLC [Member] | Successor [Member]
Cash flows from financing activities
Cash and cash equivalents at end of period	170
Potomac Electric Power Company [Member]
Cash flows from operating activities
Net income	42	187	171
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	295	256	212
(Gain) Loss on sales of assets	(8)	(46)	0
Deferred income taxes and amortization of investment tax credits	153	150	175
Other non-cash operating activities	183	54	37
Changes in assets and liabilities:
Accounts receivable	(41)	(43)	7
Receivables from and payables to affiliates, net	44	0	(2)
Inventories	1	(5)	5
Accounts payable and accrued expenses	32	(21)	(37)
Income taxes	110	(46)	(14)
Pension and non-pension postretirement benefit contributions	(32)	(14)	(11)
Other assets and liabilities	(128)	(99)	(157)
Net cash flows provided by operating activities	651	373	386
Cash flows from investing activities
Capital expenditures	(586)	(544)	(567)
Acquisitions of businesses, net	(33)
Proceeds from sales of long-lived assets	12	54	9
Purchases of investments	(30)	0	0
Change in restricted cash	(31)	3	(3)
Other investing activities	(12)	10	1
Net cash flows used in investing activities	(647)	(477)	(560)
Cash flows from financing activities
Issuance of long-term debt	4	208	412
Retirement of long-term debt	(11)	(22)	(184)
Dividends paid on common stock	(136)	(146)	(86)
Other financing activities	(3)	(9)	(4)
Contributions from parent	187	112	80
Proceeds from (Repayments of) Short-term Debt	(41)	(40)	(47)
Net cash flows provided by financing activities	0	103	171
(Decrease) Increase in cash and cash equivalents	4	(1)	(3)
Cash and cash equivalents at beginning of period	5	6	9
Cash and cash equivalents at end of period	9	5	6
Delmarva Power and Light Company [Member]
Cash flows from operating activities
Net income	(9)	76	104
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	157	148	122
Deferred income taxes and amortization of investment tax credits	109	73	110
Other non-cash operating activities	114	33	22
Changes in assets and liabilities:
Accounts receivable	(5)	(24)	1
Receivables from and payables to affiliates, net	13	3	(6)
Inventories	0	6	(2)
Accounts payable and accrued expenses	(4)	(8)	0
Increase (Decrease) Cash Collateral from Counterparties	1	(1)	0
Income taxes	28	(26)	(1)
Pension and non-pension postretirement benefit contributions	(22)	0	0
Other assets and liabilities	(72)	(14)	(82)
Net cash flows provided by operating activities	310	266	268
Cash flows from investing activities
Capital expenditures	(349)	(352)	(352)
Proceeds from sales of long-lived assets	9	0	0
Change in restricted cash	0	5	(5)
Other investing activities	4	2	(1)
Net cash flows used in investing activities	(336)	(345)	(358)
Cash flows from financing activities
Issuance of long-term debt	175	200	204
Retirement of long-term debt	(100)	(100)	(100)
Dividends paid on common stock	(54)	(92)	(100)
Other financing activities	(1)	(2)	(1)
Contributions from parent	152	75	130
Proceeds from (Repayments of) Short-term Debt	(105)	(1)	(41)
Net cash flows provided by financing activities	67	80	92
(Decrease) Increase in cash and cash equivalents	41	1	2
Cash and cash equivalents at beginning of period	5	4	2
Cash and cash equivalents at end of period	46	5	4
Atlantic City Electric Company [Member]
Cash flows from operating activities
Net income	(42)	40	46
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, and accretion, including nuclear fuel and energy contract amortization	165	175	155
Deferred income taxes and amortization of investment tax credits	22	31	38
Other non-cash operating activities	155	37	26
Changes in assets and liabilities:
Accounts receivable	(8)	(67)	6
Receivables from and payables to affiliates, net	13	1	0
Inventories	(1)	(1)	4
Accounts payable and accrued expenses	9	9	(17)
Income taxes	174	(34)	(20)
Pension and non-pension postretirement benefit contributions	(17)	(2)	(3)
Other assets and liabilities	(85)	67	24
Net cash flows provided by operating activities	385	256	259
Cash flows from investing activities
Capital expenditures	(311)	(300)	(225)
Proceeds from sales of long-lived assets	2	0	0
Change in restricted cash	(2)	(6)	0
Other investing activities	2	0	1
Net cash flows used in investing activities	(309)	(306)	(224)
Cash flows from financing activities
Repayments of Debt, Maturing in More than Three Months			(100)
Issuance of long-term debt	0	150	150
Retirement of long-term debt	(48)	(58)	(66)
Dividends paid on common stock	(63)	(12)	(26)
Other financing activities	(1)	(2)	(1)
Contributions from parent	139	95	0
Proceeds from (Repayments of) Short-term Debt	(5)	(122)	7
Net cash flows provided by financing activities	22	51	(36)
(Decrease) Increase in cash and cash equivalents	98	1	(1)
Cash and cash equivalents at beginning of period	3	2	3
Cash and cash equivalents at end of period	$ 101	$ 3	$ 2