XML 66 R26.htm IDEA: XBRL DOCUMENT v3.3.0.814
Asset Retirement Obligations (Tables)
 9 Months Ended
Sep. 30, 2015
Asset Retirement Obligation [Abstract]  
Asset retirement obligations roll forward
 
Asset Retirement Obligations
 
2015
 
(in millions)
ARO liability at January 1,
$
195.1

Accretion
6.4

Additions
3.0

Revisions
0.3

Liabilities related to divestitures
(14.8
)
Liabilities settled
(1.5
)
ARO liability at September 30,
$
188.5