Asset Impairment Expense (Tables)

9 Months Ended

Sep. 30, 2017

Impairment or Disposal of Tangible Assets Disclosure [Abstract]

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

	Three Months Ended September 30,				Nine Months Ended September 30,
(in millions)	2017		2016		2017		2016
Kazakhstan Hydroelectric	$	2	$	—	$	92	$	—
Kazakhstan CHPs	—		—		94		—
Buffalo Gap I	—		78		—		78
DPL	—		—		66		235
Tait Energy Storage	—		—		8		—
Buffalo Gap II	—		—		—		159
Other	—		1		—		1
Total	$	2	$	79	$	260	$	473