Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Condensed Statements of Cash Flows (Details) - USD ($) $ in Millions		12 Months Ended
	Feb. 26, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net cash flows provided by operating activities		$ 7,616	$ 4,457	$ 6,343
Cash flows from investing activities
Proceeds from termination of direct financing lease investment	$ 335	0	335	0
Capital expenditures		(7,624)	(6,077)	(5,395)
Cash and restricted cash acquired from Constellation		0	140	0
Change in restricted cash		66	(104)	(43)
Other investing activities		(119)	(88)	112
Net cash flows used in investing activities		(7,822)	(4,599)	(5,394)
Cash flows from financing activities
Changes in short-term borrowings		80	122	332
Issuance of long-term debt		6,709	3,463	2,055
Retirement of long-term debt		(2,687)	(1,545)	(1,589)
Dividends paid on common stock		(1,105)	(1,065)	(1,249)
Proceeds from employee stock plans		32	35	47
Other financing activities		(67)	(178)	(119)
Net cash flows provided by (used in) financing activities		4,830	411	(826)
Increase in cash and cash equivalents		4,624	269	123
Cash and cash equivalents at beginning of period		1,878	1,609	1,486
Cash and cash equivalents at end of period		6,502	1,878	1,609
Exelon Corporate [Member]
Net cash flows provided by operating activities		3,071	806	1,053
Cash flows from investing activities
Proceeds from termination of direct financing lease investment		0	335	0
Changes in Exelon intercompany money pool		(1,217)	(83)	(60)
Note receivable from affiliates		550	0	484
Capital expenditures		0	1	0
Change in restricted cash		0	0	38
Investment in affiliates		(212)	(70)	(38)
Other investing activities		(55)	(126)	15
Net cash flows used in investing activities		(934)	57	439
Cash flows from financing activities
Changes in short-term borrowings		0	0	10
Issuance of long-term debt		4,200	1,150	0
Retirement of long-term debt		(2,263)	(23)	(450)
Dividends paid on common stock		(1,105)	(1,065)	(1,249)
Proceeds from employee stock plans		32	35	47
Other financing activities		(58)	(84)	(6)
Net cash flows provided by (used in) financing activities		2,674	13	(1,648)
Increase in cash and cash equivalents		4,811	876	(156)
Cash and cash equivalents at beginning of period		879	3	159
Cash and cash equivalents at end of period		$ 5,690	$ 879	$ 3