Asset Impairment Expense (Tables)

6 Months Ended

Jun. 30, 2016

Impairment or Disposal of Tangible Assets Disclosure [Abstract]

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

	Three Months Ended June 30,				Six Months Ended June 30,
(in millions)	2016		2015		2016		2015
Buffalo Gap II	$	—	$	—	$	159	$	—
UK Wind	—		37		—		37
DPL	235		—		235		—
Other	—		—		—		8
Total asset impairment expense	$	235	$	37	$	394	$	45