XML 113 R79.htm IDEA: XBRL DOCUMENT v3.10.0.1
Property, Plant and Equipment (Asset Retirement Obligations) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset Retirement Obligation, Revision of Estimate $ 24 $ 25
Beginning balance 368 357
Additional liabilities incurred 19 1
Asset Retirement Obligation, Other [Line Items] 0 (10)
Liabilities settled (14) (21)
Accretion expense 18 16
Ending balance 415 $ 368
IPL Subsidiary [Member]    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset Retirement Obligation, Revision of Estimate 55  
DPL Subsidiary [Member]    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset Retirement Obligation, Revision of Estimate $ (32)