XML 116 R91.htm IDEA: XBRL DOCUMENT v2.4.0.6
Asset Retirement Obligations (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Sep. 30, 2010
Dec. 31, 2011
Dec. 31, 2010
Asset Retirement Obligations (Numeric) [Abstract]      
Susquehanna accrued nuclear decommissioning obligation   $ 292 $ 270
Susquehanna NDT funds   640 618
Asset Retirement Obligation [Roll Forward]      
Balance at Beginning of Period   448 426
Accretion expense   33 32
Obligations assumed in acquisition of LKE   0 103
Obligations assumed in acquisition of WPD Midlands   15 [1] 0
Obligations incurred   14 4
Changes in estimated cash flow or settlement date   5 (100)
Obligations settled   (18) (17)
Balance at End of Period   497 448
Reduction in an ARO liability related to Susquehanna nuclear plant based on a 2010 cost study 103    
Reduction in PP&E related to Susquehanna nuclear plant based on the impact of a 2010 cost study for ARO costs 103    
Asset Retirement Obligation Balance Classification (Details) [Abstract]      
Current portion   13 [2] 13 [2]
Long-term portion   484 435
Total   $ 497 $ 448
[1] Obligations required under U.K. law related to treated wood poles, gas-filled switchgear and fluid-filled cables. See Note 10 for additional information on the acquisition.
[2] Included in "Other current liabilities."