Asset Impairment Expense (Tables)

12 Months Ended

Dec. 31, 2015

Impairment or Disposal of Tangible Assets Disclosure [Abstract]

Details of Impairment of Long-Lived Assets Held and Used by Asset

Years ended December 31,	2015		2014		2013
	(in millions)
Kilroot	$	121	$	—	$	—
Buffalo Gap III	116		—		—
U.K. Wind	37		12		—
Ebute	—		67		—
East Bend (DP&L)	—		12		—
Beaver Valley	—		—		46
Conesville (DP&L)	—		—		26
Itabo (San Lorenzo)	—		—		16
Other	11		—		7
Total asset impairment expense	$	285	$	91	$	95