XML 28 R43.htm IDEA: XBRL DOCUMENT v2.4.0.6
ASSET RETIREMENT OBLIGATION: (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
item
Mar. 31, 2012
ASSET RETIREMENT OBLIGATION:    
Period after which the law requires a first review 3 years  
Period after which successive reviews are required by the law 5 years  
Accepted value of the Lima office building $ 17  
Cumulative guarantee amount 10.5  
Number of units with future closure costs recognized as an asset retirement obligation 3  
Asset retirement obligation activity    
Balance at the beginning of the period 118.2 62.0
Accretion expense 1.8 0.8
Balance at the end of the period $ 120.0 $ 62.8