Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities
Net income	$ 430	$ 1,372
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	2,396	1,957
Impairment of long-lived assets and losses on regulatory assets	239	24
Gain on sales of assets	(40)	(8)
Deferred income taxes and amortization of investment tax credits	(261)	(211)
Net fair value changes related to derivatives	194	(507)
Gain (Loss) on Investments	114	2
Other non-cash operating activities	1,056	579
Changes in assets and liabilities:
Inventories	89	159
Accounts receivable	86	253
Accounts payable and accrued expenses	(363)	(540)
Option premiums received, net	(10)	22
Collateral received, net	710	659
Income taxes	470	247
Pension and non-pension postretirement benefit contributions	(258)	(301)
Other assets and liabilities	(593)	(156)
Net cash flows provided by operating activities	4,553	3,969
Cash flows from investing activities
Capital expenditures	(4,489)	(3,460)
Proceeds from nuclear decommissioning trust fund sales	4,977	3,314
Investment in nuclear decommissioning trust funds	(5,094)	(3,437)
Acquisition of businesses, net of cash acquired	(6,642)	(28)
Proceeds from Sale of Property Held-for-sale	45	145
Proceeds from termination of direct financing lease investment	360	0
Change in restricted cash	15	(3)
Other investing activities	(49)	(77)
Net cash flows used in investing activities	(10,877)	(3,546)
Cash flows from financing activities
Changes in short-term borrowings	798	(94)
Proceeds from short-term borrowings with maturities greater than 90 days	(194)	0
Issuance of long-term debt	3,174	5,907
Retirement of long-term debt	(217)	(1,708)
Dividends paid on common stock	(582)	(537)
Proceeds from employee stock plans	17	16
Other financing activities	4	59
Net cash flows provided by financing activities	1,469	3,713
Repayments of Short-term Debt, Maturing in More than Three Months	(315)	0
(Decrease) Increase in cash and cash equivalents	(4,855)	4,136
Cash and cash equivalents at beginning of period	6,502	1,878
Cash and cash equivalents at end of period	1,647	6,014
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income	285	875
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	1,467	1,255
Impairment of long-lived assets and losses on regulatory assets	179	(1)
Gain on sales of assets	(31)	(6)
Deferred income taxes and amortization of investment tax credits	59	(65)
Net fair value changes related to derivatives	199	(396)
Gain (Loss) on Investments	114	2
Other non-cash operating activities	169	134
Changes in assets and liabilities:
Inventories	57	134
Accounts receivable	123	291
Change Receivables Payables From Affiliates	(77)	(11)
Accounts payable and accrued expenses	(228)	(369)
Option premiums received, net	(10)	22
Collateral received, net	720	682
Income taxes	41	27
Pension and non-pension postretirement benefit contributions	(117)	(122)
Other assets and liabilities	(217)	(155)
Net cash flows provided by operating activities	2,387	2,423
Cash flows from investing activities
Capital expenditures	(2,051)	(1,764)
Proceeds from nuclear decommissioning trust fund sales	4,977	3,314
Investment in nuclear decommissioning trust funds	(5,094)	(3,437)
Acquisition of businesses, net of cash acquired	(1)	(28)
Proceeds from Sale of Property Held-for-sale	30	144
Change in restricted cash	25	(16)
Other investing activities	(96)	(63)
Net cash flows used in investing activities	(2,210)	(1,850)
Cash flows from financing activities
Changes in short-term borrowings	0	(15)
Repayments of Debt, Maturing in More than Three Months	(15)	0
Issuance of long-term debt	173	1,307
Proceeds from Debt, Maturing in More than Three Months	194	0
Retirement of long-term debt	(131)	(39)
Repayments of Related Party Debt	0	(550)
Other financing activities	(39)	6
Distribution to member	(111)	(2,262)
Proceeds from Contributions from Affiliates	45	0
Change in Exelon intercompany money pool borrowings	(429)	638
Net cash flows provided by financing activities	(235)	(897)
(Decrease) Increase in cash and cash equivalents	(58)	(324)
Cash and cash equivalents at beginning of period	431	780
Cash and cash equivalents at end of period	373	456
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income	260	189
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	379	352
Gain on sales of assets	(5)	0
Deferred income taxes and amortization of investment tax credits	(222)	(36)
Other non-cash operating activities	83	222
Changes in assets and liabilities:
Inventories	7	(19)
Accounts receivable	(36)	(57)
Change Receivables Payables From Affiliates	1	(10)
Accounts payable and accrued expenses	(42)	(53)
Collateral received, net	(10)	0
Income taxes	261	239
Pension and non-pension postretirement benefit contributions	(35)	(125)
Other assets and liabilities	38	26
Net cash flows provided by operating activities	1,128	800
Cash flows from investing activities
Capital expenditures	(1,334)	(1,061)
Other investing activities	21	17
Net cash flows used in investing activities	(1,313)	(1,044)
Cash flows from financing activities
Changes in short-term borrowings	259	(199)
Issuance of long-term debt	1,200	400
Retirement of long-term debt	0	(260)
Dividends paid on common stock	(183)	(150)
Other financing activities	17	5
Contributions from parent	(113)	(45)
Net cash flows provided by financing activities	854	229
(Decrease) Increase in cash and cash equivalents	669	(15)
Cash and cash equivalents at beginning of period	67	66
Cash and cash equivalents at end of period	736	51
PECO Energy Co [Member]
Cash flows from operating activities
Net income	224	209
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	134	131
Deferred income taxes and amortization of investment tax credits	(51)	(4)
Other non-cash operating activities	27	45
Changes in assets and liabilities:
Inventories	19	21
Accounts receivable	(1)	(18)
Change Receivables Payables From Affiliates	(2)	(2)
Accounts payable and accrued expenses	(19)	3
Income taxes	31	57
Pension and non-pension postretirement benefit contributions	(29)	(15)
Other assets and liabilities	(96)	(60)
Net cash flows provided by operating activities	339	375
Cash flows from investing activities
Capital expenditures	(299)	(289)
Change in restricted cash	0	(1)
Other investing activities	8	9
Net cash flows used in investing activities	(291)	(281)
Cash flows from financing activities
Dividends paid on common stock	(139)	(139)
Other financing activities	1	0
Change in Exelon intercompany money pool borrowings		41
Net cash flows provided by financing activities	(140)	(98)
(Decrease) Increase in cash and cash equivalents	(92)	(4)
Cash and cash equivalents at beginning of period	295	30
Cash and cash equivalents at end of period	203	26
Baltimore Gas and Electric Company [Member]
Cash flows from operating activities
Net income	135	157
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	206	192
Impairment of long-lived assets and losses on regulatory assets	52
Deferred income taxes and amortization of investment tax credits	(17)	(54)
Other non-cash operating activities	60	76
Changes in assets and liabilities:
Inventories	6	23
Accounts receivable	11	25
Change Receivables Payables From Affiliates	6	(2)
Accounts payable and accrued expenses	(5)	(59)
Collateral received, net	0	(23)
Income taxes	46	(6)
Pension and non-pension postretirement benefit contributions	(42)	(9)
Other assets and liabilities	(3)	61
Net cash flows provided by operating activities	489	489
Cash flows from investing activities
Capital expenditures	(392)	(304)
Change in restricted cash	5	21
Other investing activities	12	8
Net cash flows used in investing activities	(375)	(275)
Cash flows from financing activities
Changes in short-term borrowings	2	120
Retirement of long-term debt	(39)	(37)
Dividends paid on common stock	(90)	(77)
Other financing activities	2	14
Contributions from parent	(21)	0
Dividends paid on preference stock	(6)	(6)
Net cash flows provided by financing activities	(118)	(254)
(Decrease) Increase in cash and cash equivalents	(4)	(40)
Cash and cash equivalents at beginning of period	9	64
Cash and cash equivalents at end of period	5	24
Pepco Holdings LLC [Member] | Successor [Member]
Cash flows from financing activities
Cash and cash equivalents at end of period	294
Pepco Holdings LLC [Member] | Predecessor [Member]
Cash flows from operating activities
Net income		106
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization		307
Deferred income taxes and amortization of investment tax credits		(73)
Net fair value changes related to derivatives		0
Other non-cash operating activities		101
Changes in assets and liabilities:
Inventories		0
Accounts receivable		(196)
Change Receivables Payables From Affiliates		0
Accounts payable and accrued expenses		19
Collateral received, net		0
Income taxes		0
Pension and non-pension postretirement benefit contributions		(8)
Other assets and liabilities		(63)
Net cash flows provided by operating activities		339
Cash flows from investing activities
Capital expenditures		(562)
Purchases of investments		0
Change in restricted cash		11
Other investing activities		(2)
Net cash flows used in investing activities		(553)
Cash flows from financing activities
Changes in short-term borrowings		(69)
Proceeds from short-term borrowings with maturities greater than 90 days		0
Issuance of long-term debt		408
Retirement of long-term debt		(138)
Dividends paid on common stock		(137)
Common stock issued for the Direct Stock Purchase and Dividend Reinvestment Plan and employee-related compensation		19
Distribution to member		0
Other financing activities		24
Contributions from parent		0
Change in Exelon intercompany money pool borrowings		0
Issuance of preferred stock		36
Net cash flows provided by financing activities		233
(Decrease) Increase in cash and cash equivalents		19
Cash and cash equivalents at beginning of period	26	15
Cash and cash equivalents at end of period		34
Potomac Electric Power Company [Member]
Cash flows from operating activities
Net income	(60)	68
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	144	125
Deferred income taxes and amortization of investment tax credits	(20)	(31)
Other non-cash operating activities	158	33
Changes in assets and liabilities:
Inventories	1	(4)
Accounts receivable	(41)	(99)
Change Receivables Payables From Affiliates	47	2
Accounts payable and accrued expenses	(19)	(9)
Income taxes	165	0
Pension and non-pension postretirement benefit contributions	(3)	(6)
Other assets and liabilities	(47)	(36)
Net cash flows provided by operating activities	365	105
Cash flows from investing activities
Capital expenditures	(256)	(254)
Proceeds from Sale of Property Held-for-sale	12
Purchases of investments	(31)	0
Change in restricted cash	(31)	3
Other investing activities	(1)	3
Net cash flows used in investing activities	(307)	(248)
Cash flows from financing activities
Changes in short-term borrowings	64	104
Issuance of long-term debt	1	208
Retirement of long-term debt	(5)	(17)
Dividends paid on common stock	(55)	(31)
Other financing activities	0	9
Contributions from parent	(187)	(112)
Net cash flows provided by financing activities	64	159
(Decrease) Increase in cash and cash equivalents	122	16
Cash and cash equivalents at beginning of period	5	6
Cash and cash equivalents at end of period	127	22
Delmarva Power and Light Company [Member]
Cash flows from operating activities
Net income	(60)	40
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	76	74
Deferred income taxes and amortization of investment tax credits	(23)	(26)
Other non-cash operating activities	121	22
Changes in assets and liabilities:
Inventories	1	6
Accounts receivable	30	(43)
Change Receivables Payables From Affiliates	15	3
Accounts payable and accrued expenses	(2)	(9)
Collateral received, net	1	0
Income taxes	66	0
Other assets and liabilities	(51)	(4)
Net cash flows provided by operating activities	220	115
Cash flows from investing activities
Capital expenditures	(182)	(154)
Change in restricted cash	(1)	5
Other investing activities	3	1
Net cash flows used in investing activities	(180)	(148)
Cash flows from financing activities
Changes in short-term borrowings	105	76
Issuance of long-term debt	0	200
Retirement of long-term debt	0	(100)
Dividends paid on common stock	(38)	(62)
Other financing activities	0	2
Contributions from parent	(113)	(75)
Net cash flows provided by financing activities	(30)	35
(Decrease) Increase in cash and cash equivalents	10	2
Cash and cash equivalents at beginning of period	5	4
Cash and cash equivalents at end of period	15	6
Atlantic City Electric Company [Member]
Cash flows from operating activities
Net income	(97)	15
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	81	86
Deferred income taxes and amortization of investment tax credits	28	(9)
Other non-cash operating activities	138	17
Changes in assets and liabilities:
Inventories	(2)	(1)
Accounts receivable	31	(55)
Change Receivables Payables From Affiliates	8	0
Accounts payable and accrued expenses	6	37
Income taxes	181	(1)
Other assets and liabilities	(110)	(24)
Net cash flows provided by operating activities	208	83
Cash flows from investing activities
Capital expenditures	(164)	(138)
Proceeds from Sale of Property Held-for-sale	2	0
Change in restricted cash	1	0
Other investing activities	1	(2)
Net cash flows used in investing activities	(160)	(140)
Cash flows from financing activities
Changes in short-term borrowings	5	(91)
Retirement of long-term debt	(22)	(21)
Dividends paid on common stock	(11)	(12)
Other financing activities	1	0
Contributions from parent	(139)	0
Net cash flows provided by financing activities	100	58
(Decrease) Increase in cash and cash equivalents	148	1
Cash and cash equivalents at beginning of period	3	2
Cash and cash equivalents at end of period	$ 151	$ 3