Asset Impairment Expense (Tables)

12 Months Ended

Dec. 31, 2019

Impairment or Disposal of Tangible Assets Disclosure [Abstract]

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

Year ended December 31, (in millions)	2019		2018		2017
Kilroot and Ballylumford	$	115	$	—	$	37
Hawaii	60		—		—
Shady Point	—		157		—
Nejapa	—		37		—
DPL	—		—		175
Laurel Mountain	—		—		121
Kazakhstan Hydroelectric	—		—		92
Kazakhstan CHPs	—		—		94
Other	10		14		18
Total	$	185	$	208	$	537