Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Condensed Balance Sheet (Details) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 17, 2012
Current assets
Cash and cash equivalents		$ 898	$ 635	$ 6,502	$ 1,878
Prepaid Taxes		0	1,250
Accounts receivable, net
Other		1,132	1,201
Regulatory assets		1,267	1,342
Other		1,242	930
Total current assets		11,834	12,412
Property, plant and equipment, net		74,202	71,555
Deferred debits and other assets
Regulatory assets		8,021	10,046
Other		1,322	1,472
Total assets (a)	[1]	116,700	114,904
Current liabilities
Short-term Debt		929	1,267
Due to Affiliate, Current		360	706
Long-term debt due within one year		2,088	2,430
Accounts payable		3,532	3,441
Unamortized energy contract liabilities		231	407
Accrued expenses		1,835	3,460
Regulatory liabilities		523	602
Other		982	981
Total current liabilities		10,796	13,457
Long-term debt		32,176	31,575
Deferred credits and other liabilities
Regulatory liabilities		9,865	4,187
Pension obligations		3,736	4,248
Non-pension postretirement benefit obligations		2,093	1,848
Other		2,097	1,827
Total liabilities	[1]	84,568	87,292
Commitments and Contingencies						$ 1,000
Shareholders’ equity
Common stock		18,964	18,794
Treasury stock, at cost (2 shares and 35 shares at December 31, 2017 and 2016, respectively)		(123)	(2,327)
Retained earnings		13,503	12,030
Accumulated other comprehensive loss, net		(2,487)	(2,660)
Total shareholders’ equity		29,857	25,837
Liabilities and Equity		116,700	114,904
Exelon Corporate [Member]
Current assets
Cash and cash equivalents		74	18	$ 5,690	$ 879
Accounts receivable, net
Other		431	73
Accounts receivable from affiliates		33	48
Receivables from affiliates		217	88
Regulatory assets		284	263
Other		4	1,250
Total current assets		1,043	1,740
Property, plant and equipment, net		50	51
Deferred debits and other assets
Regulatory assets		3,697	4,033
Investments in affiliates		39,272	34,869
Deferred income taxes		1,431	2,107
Receivable from affiliates		910	922
Other		234	256
Total deferred debits and other assets		45,544	42,187
Total assets (a)		46,637	43,978
Current liabilities
Short-term Debt		500	0
Due to Affiliate, Current		360	706
Long-term debt due within one year		0	570
Accounts payable		2	2
Accrued expenses		99	489
Regulatory liabilities		16	16
Liability, Defined Benefit Plan, Current		65	58
Other		46	50
Total current liabilities		1,088	1,891
Long-term debt		7,161	7,193
Deferred credits and other liabilities
Regulatory liabilities		15	31
Pension obligations		7,792	8,608
Non-pension postretirement benefit obligations		322	7
Deferred income taxes		220	226
Other		180	182
Deferred Credits and Other Liabilities, Noncurrent		8,529	9,054
Total liabilities		16,778	18,138
Commitments and Contingencies
Shareholders’ equity
Common stock		18,966	18,797
Treasury stock, at cost (2 shares and 35 shares at December 31, 2017 and 2016, respectively)		(123)	(2,327)
Retained earnings		13,503	12,030
Accumulated other comprehensive loss, net		(2,487)	(2,660)
Total shareholders’ equity		29,859	25,840
Liabilities and Equity		$ 46,637	$ 43,978

[1] Exelon’s consolidated assets include $9,565 million and $8,893 million at December 31, 2017 and December 31, 2016, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,612 million and $3,356 million at December 31, 2017 and December 31, 2016, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 2–Variable Interest Entities.