Significant Accounting Policies Revenue Initial Application Period Cumulative Effect Transition (Tables)

9 Months Ended

Sep. 30, 2018

Revenue from Contract with Customer [Abstract]

Cummulative Effect of New Accounting Pronouncement Adoption Revenue from Contract with Customer [Table Text Block]

Three Months Ended September 30, 2017	Exelon			Generation			ComEd			PECO		BGE			PHI			Pepco			DPL			ACE
Operating Revenues - As reported
Competitive business revenues	$	4,456		$	—		$	—		$	—	$	—		$	—		$	—		$	—		$	—
Rate-regulated utility revenues	4,313			—			—			—		—			—			—			—			—
Operating revenues	—			4,455			—			—		—			—			—			—			—
Electric operating revenues	—			—			1,568			660		657			1,280			603			307			370
Natural gas operating revenues	—			—			—			53		78			18			—			18			—
Operating revenues from affiliates	—			296			3			2		3			12			1			2			—
Total operating revenues	$	8,769		$	4,751		$	1,571		$	715	$	738		$	1,310		$	604		$	327		$	370
Operating Revenues - Adjustments
Competitive business revenues	$	(1	)	$	—		$	—		$	—	$	—		$	—		$	—		$	—		$	—
Rate-regulated utility revenues	(54		)	—			—			—		—			—			—			—			—
Operating revenues	—			(1		)	—			—		—			—			—			—			—
Electric operating revenues	—			—			(16		)	—		(31		)	(2		)	(3		)	1			—
Natural gas operating revenues	—			—			—			—		(5		)	—			—			—			—
Revenues from alternative revenue programs	54			—			16			—		36			2			3			(1		)	—
Operating revenues from affiliates	—			—			—			—		—			—			—			—			—
Total operating revenues	$	(1	)	$	(1	)	$	—		$	—	$	—		$	—		$	—		$	—		$	—
Operating Revenues - Retrospective application
Competitive business revenues	$	4,455		$	—		$	—		$	—	$	—		$	—		$	—		$	—		$	—
Rate-regulated utility revenues	4,259			—			—			—		—			—			—			—			—
Operating revenues	—			4,454			—			—		—			—			—			—			—
Electric operating revenues	—			—			1,552			660		626			1,278			600			308			370
Natural gas operating revenues	—			—			—			53		73			18			—			18			—
Revenues from alternative revenue programs	54			—			16			—		36			2			3			(1		)	—
Operating revenues from affiliates	—			296			3			2		3			12			1			2			—
Total operating revenues	$	8,768		$	4,750		$	1,571		$	715	$	738		$	1,310		$	604		$	327		$	370

Nine Months Ended September 30, 2017	Exelon			Generation		ComEd			PECO		BGE			PHI			Pepco			DPL			ACE
Operating Revenues - As reported
Competitive business revenues	$	12,924		$	—	$	—		$	—	$	—		$	—		$	—		$	—		$	—
Rate-regulated utility revenues	12,225			—		—			—		—			—			—			—			—
Operating revenues	—			12,918		—			—		—			—			—			—			—
Electric operating revenues	—			—		4,215			1,798		1,890			3,417			1,645			860			913
Natural gas operating revenues	—			—		—			338		461			105			—			105			—
Operating revenues from affiliates	—			894		12			5		12			35			4			6			2
Total operating revenues	$	25,149		$	13,812	$	4,227		$	2,141	$	2,363		$	3,557		$	1,649		$	971		$	915
Operating Revenues - Adjustments
Competitive business revenues	$	31		$	—	$	—		$	—	$	—		$	—		$	—		$	—		$	—
Rate-regulated utility revenues	(191		)	—		—			—		—			—			—			—			—
Operating revenues	—			31		—			—		—			—			—			—			—
Electric operating revenues	—			—		(48		)	—		(79		)	(41		)	(23		)	(9		)	(9		)
Natural gas operating revenues	—			—		—			—		(23		)	—			—			—			—
Revenues from alternative revenue programs	191			—		48			—		102			41			23			9			9
Operating revenues from affiliates	—			—		—			—		—			—			—			—			—
Total operating revenues	$	31		$	31	$	—		$	—	$	—		$	—		$	—		$	—		$	—
Operating Revenues - Retrospective application
Competitive business revenues	$	12,955		$	—	$	—		$	—	$	—		$	—		$	—		$	—		$	—
Rate-regulated utility revenues	12,034			—		—			—		—			—			—			—			—
Operating revenues	—			12,949		—			—		—			—			—			—			—
Electric operating revenues	—			—		4,167			1,798		1,811			3,376			1,622			851			904
Natural gas operating revenues	—			—		—			338		438			105			—			105			—
Revenues from alternative revenue programs	191			—		48			—		102			41			23			9			9
Operating revenues from affiliates	—			894		12			5		12			35			4			6			2
Total operating revenues	$	25,180		$	13,843	$	4,227		$	2,141	$	2,363		$	3,557		$	1,649		$	971		$	915