XML 39 R34.htm IDEA: XBRL DOCUMENT v3.24.0.1
Asset Retirement Obligations (Tables)
 12 Months Ended
Dec. 31, 2023
Asset Retirement Obligation Disclosure [Abstract]  
Schedule of Reconciliation of the Carrying Amount of AROs

A reconciliation of the beginning and ending aggregate carrying amount of AROs is as follows:

 

(millions)

 

2023

 

 

2022

 

Beginning balance

 

$

628

 

 

$

599

 

Liabilities incurred

 

 

7

 

 

 

6

 

Liabilities settled

 

 

(14

)

 

 

(1

)

Accretion expense

 

 

29

 

 

 

26

 

Revisions in estimated cash flows(1)

 

 

81

 

 

 

(2

)

Ending balance

 

$

731

 

 

$

628

 
(1)
In 2023, there was an increase in estimated costs associated with certain coal-fired generating units, including revisions following the approval of closure plans for a facility previously taken out of service.