Consolidated Statements of Cash Flows (Unaudited) - USD ($)		3 Months Ended
	Mar. 31, 2016	Mar. 31, 2016	Mar. 23, 2016	Mar. 31, 2015
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income		$ 123,000,000		$ 738,000,000
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		1,063,000,000		948,000,000
Impairment of long-lived assets		119,000,000		0
Gain on sales of assets		(9,000,000)		(1,000,000)
Deferred income taxes and amortization of investment tax credits		(127,000,000)		(129,000,000)
Net fair value changes related to derivatives		(107,000,000)		(91,000,000)
Gain (Loss) on Investments		55,000,000		47,000,000
Other non-cash operating activities		804,000,000		344,000,000
Changes in assets and liabilities:
Inventories		142,000,000		291,000,000
Accounts receivable		117,000,000		(270,000,000)
Accounts payable and accrued expenses		571,000,000		468,000,000
Option premiums received, net		17,000,000		5,000,000
Collateral received, net		206,000,000		257,000,000
Income taxes		47,000,000		174,000,000
Pension and non-pension postretirement benefit contributions		(239,000,000)		(269,000,000)
Other assets and liabilities		(311,000,000)		(250,000,000)
Net cash flows provided by operating activities		1,473,000,000		1,490,000,000
Cash flows from investing activities
Capital expenditures		(2,202,000,000)		(1,784,000,000)
Proceeds from nuclear decommissioning trust fund sales		2,240,000,000		1,681,000,000
Investment in nuclear decommissioning trust funds		(2,297,000,000)		(1,747,000,000)
Acquisition of businesses, net of cash acquired		(6,645,000,000)		(15,000,000)
Proceeds from Sale of Property Held-for-sale		0		142,000,000
Proceeds from termination of direct financing lease investment		360,000,000		0
Change in restricted cash		(2,000,000)		(26,000,000)
Other investing activities		(2,000,000)		(2,000,000)
Net cash flows used in investing activities		8,548,000,000		1,751,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from Short-term Debt, Maturing in More than Three Months		123,000,000		0
Changes in short-term borrowings		(1,647,000,000)		141,000,000
Proceeds from Issuance of Long-term Debt		151,000,000		1,206,000,000
Retirement of long-term debt		(116,000,000)		(580,000,000)
Dividends paid on common stock		(287,000,000)		(269,000,000)
Proceeds from employee stock plans		9,000,000		8,000,000
Other financing activities		(6,000,000)		16,000,000
Net cash flows provided by financing activities		1,533,000,000		208,000,000
Decrease in cash and cash equivalents		(5,542,000,000)		(53,000,000)
Cash and cash equivalents at beginning of period		6,502,000,000	$ 6,502,000,000	1,878,000,000
Cash and cash equivalents at end of period	$ 960,000,000	960,000,000		1,825,000,000
Exelon Generation Co L L C [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income		257,000,000		485,000,000
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		667,000,000		591,000,000
Impairment of long-lived assets		119,000,000		0
Gain on sales of assets		0		1,000,000
Deferred income taxes and amortization of investment tax credits		(68,000,000)		(89,000,000)
Net fair value changes related to derivatives		(106,000,000)		(165,000,000)
Gain (Loss) on Investments		55,000,000		47,000,000
Other non-cash operating activities		51,000,000		45,000,000
Changes in assets and liabilities:
Inventories		93,000,000		228,000,000
Accounts receivable		173,000,000		24,000,000
Change Receivables Payables From Affiliates		17,000,000		(10,000,000)
Accounts payable and accrued expenses		363,000,000		254,000,000
Option premiums received, net		(17,000,000)		5,000,000
Collateral received, net		198,000,000		288,000,000
Income taxes		(60,000,000)		(104,000,000)
Pension and non-pension postretirement benefit contributions		(112,000,000)		(107,000,000)
Other assets and liabilities		(148,000,000)		(232,000,000)
Net cash flows provided by operating activities		782,000,000		837,000,000
Cash flows from investing activities
Capital expenditures		(1,125,000,000)		(937,000,000)
Proceeds from nuclear decommissioning trust fund sales		2,240,000,000		1,681,000,000
Investment in nuclear decommissioning trust funds		(2,297,000,000)		(1,747,000,000)
Acquisition of businesses, net of cash acquired		(1,000,000)		(15,000,000)
Proceeds from Sale of Property Held-for-sale		0		142,000,000
Change in restricted cash		4,000,000		(21,000,000)
Other investing activities		(25,000,000)		(2,000,000)
Changes in Exelon intercompany money pool		(1,183,000,000)		936,000,000
Net cash flows used in investing activities		1,204,000,000		899,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Changes in short-term borrowings		(1,377,000,000)		1,000,000
Proceeds from Debt, Maturing in More than Three Months		123,000,000
Retirement of long-term debt		(94,000,000)		(18,000,000)
Proceeds from Issuance of Debt		151,000,000		806,000,000
Repayments of Related Party Debt		0		(550,000,000)
Changes in Exelon intercompany money pool		(1,183,000,000)		936,000,000
Other financing activities		(5,000,000)		3,000,000
Distribution to member		(55,000,000)		(1,356,000,000)
Proceeds from Contributions from Affiliates		44,000,000		0
Net cash flows provided by financing activities		368,000,000		(186,000,000)
Decrease in cash and cash equivalents		(54,000,000)		(248,000,000)
Cash and cash equivalents at beginning of period		431,000,000	431,000,000	780,000,000
Cash and cash equivalents at end of period	377,000,000	377,000,000		532,000,000
Commonwealth Edison Co [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income		115,000,000		90,000,000
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		189,000,000		175,000,000
Gain on sales of assets		(5,000,000)		0
Deferred income taxes and amortization of investment tax credits		(70,000,000)		(35,000,000)
Other non-cash operating activities		32,000,000		126,000,000
Changes in assets and liabilities:
Inventories		(7,000,000)		(10,000,000)
Accounts receivable		(69,000,000)		38,000,000
Change Receivables Payables From Affiliates		0		2,000,000
Accounts payable and accrued expenses		(207,000,000)		121,000,000
Collateral received, net		(7,000,000)		5,000,000
Income taxes		20,000,000		131,000,000
Pension and non-pension postretirement benefit contributions		(32,000,000)		(121,000,000)
Other assets and liabilities		14,000,000		9,000,000
Net cash flows provided by operating activities		284,000,000		251,000,000
Cash flows from investing activities
Capital expenditures		639,000,000		530,000,000
Other investing activities		(13,000,000)		(7,000,000)
Net cash flows used in investing activities		(626,000,000)		(523,000,000)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Changes in short-term borrowings		(349,000,000)		(21,000,000)
Proceeds from Issuance of Long-term Debt		0		(400,000,000)
Dividends paid on common stock		(91,000,000)		75,000,000
Other financing activities		1,000,000		(4,000,000)
Contributions from parent		(39,000,000)		14,000,000
Net cash flows provided by financing activities		296,000,000		314,000,000
Decrease in cash and cash equivalents		(46,000,000)		42,000,000
Cash and cash equivalents at beginning of period		67,000,000	67,000,000	66,000,000
Cash and cash equivalents at end of period	21,000,000	21,000,000		108,000,000
PECO Energy Co [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income		124,000,000		139,000,000
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		67,000,000		62,000,000
Deferred income taxes and amortization of investment tax credits		(23,000,000)		(5,000,000)
Other non-cash operating activities		24,000,000		44,000,000
Changes in assets and liabilities:
Inventories		24,000,000		34,000,000
Accounts receivable		(51,000,000)		(115,000,000)
Change Receivables Payables From Affiliates		4,000,000		5,000,000
Accounts payable and accrued expenses		(18,000,000)		1,000,000
Income taxes		29,000,000		67,000,000
Pension and non-pension postretirement benefit contributions		(29,000,000)		(12,000,000)
Other assets and liabilities		(95,000,000)		(70,000,000)
Net cash flows provided by operating activities		138,000,000		158,000,000
Cash flows from investing activities
Capital expenditures		(195,000,000)		(148,000,000)
Changes in Exelon intercompany money pool		(160,000,000)		0
Other investing activities		4,000,000		4,000,000
Changes in Exelon intercompany money pool				65,000,000
Net cash flows used in investing activities		351,000,000		144,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Changes in Exelon intercompany money pool				65,000,000
Dividends paid on common stock		(69,000,000)		(70,000,000)
Other financing activities		0		1,000,000
Net cash flows provided by financing activities		(69,000,000)		(6,000,000)
Decrease in cash and cash equivalents		(282,000,000)		8,000,000
Cash and cash equivalents at beginning of period		295,000,000	295,000,000	30,000,000
Cash and cash equivalents at end of period	13,000,000	13,000,000		38,000,000
Baltimore Gas and Electric Company [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income		101,000,000		109,000,000
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		109,000,000		106,000,000
Deferred income taxes and amortization of investment tax credits		(26,000,000)		(33,000,000)
Other non-cash operating activities		44,000,000		64,000,000
Changes in assets and liabilities:
Inventories		17,000,000		38,000,000
Accounts receivable		(44,000,000)		(141,000,000)
Change Receivables Payables From Affiliates		7,000,000		(8,000,000)
Accounts payable and accrued expenses		(3,000,000)		14,000,000
Collateral received, net		0		(27,000,000)
Income taxes		78,000,000		26,000,000
Pension and non-pension postretirement benefit contributions		(38,000,000)		(4,000,000)
Other assets and liabilities		(30,000,000)		99,000,000
Net cash flows provided by operating activities		273,000,000		281,000,000
Cash flows from investing activities
Capital expenditures		(176,000,000)		(136,000,000)
Change in restricted cash		(20,000,000)		2,000,000
Other investing activities		5,000,000		2,000,000
Net cash flows used in investing activities		191,000,000		132,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Changes in short-term borrowings		60,000,000		120,000,000
Dividends paid on common stock		(45,000,000)		(36,000,000)
Other financing activities		(1,000,000)		13,000,000
Contributions from parent		(21,000,000)		0
Dividends paid on preference stock		(3,000,000)		(3,000,000)
Net cash flows provided by financing activities		(86,000,000)		(172,000,000)
Decrease in cash and cash equivalents		(4,000,000)		(23,000,000)
Cash and cash equivalents at beginning of period		9,000,000	9,000,000	64,000,000
Cash and cash equivalents at end of period	5,000,000	5,000,000		41,000,000
Pepco Holdings, LLC [Member] | Predecessor [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income			19,000,000	53,000,000
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			152,000,000	155,000,000
Deferred income taxes and amortization of investment tax credits			(19,000,000)	(49,000,000)
Net fair value changes related to derivatives			(18,000,000)	0
Other non-cash operating activities			(46,000,000)	57,000,000
Changes in assets and liabilities:
Inventories			4,000,000	(3,000,000)
Accounts receivable			28,000,000	(214,000,000)
Change Receivables Payables From Affiliates			0	0
Accounts payable and accrued expenses			(42,000,000)	(43,000,000)
Collateral received, net			(1,000,000)	0
Income taxes			12,000,000	(3,000,000)
Pension and non-pension postretirement benefit contributions			4,000,000	5,000,000
Other assets and liabilities			9,000,000	25,000,000
Net cash flows provided by operating activities			264,000,000	157,000,000
Cash flows from investing activities
Capital expenditures			(273,000,000)	(246,000,000)
Purchases of investments			(68,000,000)	0
Change in restricted cash			3,000,000	9,000,000
Other investing activities			(5,000,000)	2,000,000
Changes in Exelon intercompany money pool			0	0
Net cash flows used in investing activities			343,000,000	235,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from Short-term Debt, Maturing in More than Three Months			500,000,000	0
Changes in short-term borrowings			121,000,000	(74,000,000)
Proceeds from Issuance of Long-term Debt			0	208,000,000
Retirement of long-term debt			(11,000,000)	(22,000,000)
Changes in Exelon intercompany money pool			0	0
Dividends paid on common stock			0	(68,000,000)
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan			2,000,000	8,000,000
Other financing activities			(2,000,000)	13,000,000
Proceeds from Issuance of Preferred Stock and Preference Stock			0	18,000,000
Net cash flows provided by financing activities			372,000,000	205,000,000
Decrease in cash and cash equivalents			293,000,000	127,000,000
Cash and cash equivalents at beginning of period	319,000,000	26,000,000	26,000,000	15,000,000
Cash and cash equivalents at end of period			319,000,000	142,000,000
Pepco Holdings, LLC [Member] | Successor [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income	(309,000,000)
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	14,000,000
Deferred income taxes and amortization of investment tax credits	112,000,000
Net fair value changes related to derivatives	0
Other non-cash operating activities	(410,000,000)
Changes in assets and liabilities:
Inventories	0
Accounts receivable	(16,000,000)
Change Receivables Payables From Affiliates	(46,000,000)
Accounts payable and accrued expenses	4,000,000
Collateral received, net	0
Income taxes	7,000,000
Pension and non-pension postretirement benefit contributions	0
Other assets and liabilities	25,000,000
Net cash flows provided by operating activities	43,000,000
Cash flows from investing activities
Capital expenditures	(29,000,000)
Purchases of investments	(2,000,000)
Change in restricted cash	(1,000,000)
Other investing activities	2,000,000
Changes in Exelon intercompany money pool	(53,000,000)
Net cash flows used in investing activities	$ 30,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from Short-term Debt, Maturing in More than Three Months
Changes in short-term borrowings	$ 20,000,000
Proceeds from Issuance of Long-term Debt	0
Retirement of long-term debt	0
Changes in Exelon intercompany money pool	(53,000,000)
Dividends paid on common stock	0
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan	0
Other financing activities	0
Proceeds from Issuance of Preferred Stock and Preference Stock	0
Net cash flows provided by financing activities	(181,000,000)
Decrease in cash and cash equivalents	(168,000,000)
Cash and cash equivalents at beginning of period	319,000,000
Cash and cash equivalents at end of period	151,000,000	151,000,000	319,000,000
PEPCO Holdings Inc [Member] | Predecessor [Member]
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			152,000,000	155,000,000
PEPCO Holdings Inc [Member] | Successor [Member]
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	14,000,000
Potomac Electric Power Company [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income		(108,000,000)		26,000,000
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		75,000,000		62,000,000
Deferred income taxes and amortization of investment tax credits		(31,000,000)		12,000,000
Other non-cash operating activities		153,000,000		23,000,000
Changes in assets and liabilities:
Inventories		(1,000,000)		6,000,000
Accounts receivable		24,000,000		93,000,000
Change Receivables Payables From Affiliates		(55,000,000)		(21,000,000)
Accounts payable and accrued expenses		4,000,000		(6,000,000)
Income taxes		151,000,000		0
Pension and non-pension postretirement benefit contributions		1,000,000		0
Other assets and liabilities		(9,000,000)		(18,000,000)
Net cash flows provided by operating activities		258,000,000		33,000,000
Cash flows from investing activities
Capital expenditures		(109,000,000)		(119,000,000)
Purchases of investments		(31,000,000)		0
Change in restricted cash		2,000,000		3,000,000
Other investing activities		2,000,000		3,000,000
Net cash flows used in investing activities		136,000,000		113,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Changes in short-term borrowings		64,000,000		104,000,000
Proceeds from Issuance of Long-term Debt		0		208,000,000
Retirement of long-term debt		0		(12,000,000)
Dividends paid on common stock		(39,000,000)		0
Other financing activities		0		4,000,000
Contributions from parent		0		(112,000,000)
Net cash flows provided by financing activities		(103,000,000)		200,000,000
Decrease in cash and cash equivalents		19,000,000		120,000,000
Cash and cash equivalents at beginning of period		5,000,000	5,000,000	6,000,000
Cash and cash equivalents at end of period	24,000,000	24,000,000		126,000,000
Delmarva Power and Light Company [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income		(72,000,000)		32,000,000
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		39,000,000		39,000,000
Deferred income taxes and amortization of investment tax credits		4,000,000		(21,000,000)
Other non-cash operating activities		118,000,000		12,000,000
Changes in assets and liabilities:
Inventories		1,000,000		5,000,000
Accounts receivable		4,000,000		(82,000,000)
Change Receivables Payables From Affiliates		20,000,000		4,000,000
Accounts payable and accrued expenses		3,000,000		(12,000,000)
Collateral received, net		1,000,000		0
Income taxes		52,000,000		0
Other assets and liabilities		(9,000,000)		14,000,000
Net cash flows provided by operating activities		147,000,000		57,000,000
Cash flows from investing activities
Capital expenditures		(81,000,000)		(68,000,000)
Change in restricted cash		0		5,000,000
Other investing activities		0		2,000,000
Net cash flows used in investing activities		81,000,000		61,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Changes in short-term borrowings		30,000,000		(69,000,000)
Dividends paid on common stock		(38,000,000)		(62,000,000)
Net cash flows provided by financing activities		(68,000,000)		7,000,000
Decrease in cash and cash equivalents		(2,000,000)		3,000,000
Cash and cash equivalents at beginning of period		5,000,000	5,000,000	4,000,000
Cash and cash equivalents at end of period	3,000,000	3,000,000		7,000,000
Atlantic City Electric Company [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income		(100,000,000)		9,000,000
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		40,000,000		43,000,000
Deferred income taxes and amortization of investment tax credits		33,000,000		(5,000,000)
Other non-cash operating activities		132,000,000		8,000,000
Changes in assets and liabilities:
Inventories		(2,000,000)		(1,000,000)
Accounts receivable		5,000,000		(44,000,000)
Change Receivables Payables From Affiliates		20,000,000		2,000,000
Accounts payable and accrued expenses		(19,000,000)		(21,000,000)
Income taxes				0
Pension and non-pension postretirement benefit contributions		168,000,000
Other assets and liabilities		(3,000,000)		20,000,000
Net cash flows provided by operating activities		246,000,000		63,000,000
Cash flows from investing activities
Capital expenditures		(101,000,000)		(54,000,000)
Change in restricted cash		1,000,000		0
Other investing activities		0		1,000,000
Net cash flows used in investing activities		100,000,000		53,000,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Changes in short-term borrowings		5,000,000		(16,000,000)
Retirement of long-term debt		(11,000,000)		(10,000,000)
Dividends paid on common stock		(11,000,000)		(12,000,000)
Net cash flows provided by financing activities		(27,000,000)		(6,000,000)
Decrease in cash and cash equivalents		119,000,000		4,000,000
Cash and cash equivalents at beginning of period		3,000,000	$ 3,000,000	2,000,000
Cash and cash equivalents at end of period	$ 122,000,000	$ 122,000,000		$ 6,000,000