XML 23 R12.htm IDEA: XBRL DOCUMENT v3.4.0.3
Asset Retirement Obligations
3 Months Ended
Mar. 31, 2016
Asset Retirement Obligation Disclosure [Abstract]  
Asset Retirement Obligations
Asset Retirement Obligations
 
The change in our asset retirement obligations during the three months ended March 31, 2016 is set forth below:
 
Three Months Ended
March 31, 2016
 
(In millions)
Asset retirement obligations as of the beginning of the period, including current portion
$
225.9

Liabilities incurred
2.1

Liabilities settled
(4.7
)
Accretion expense
10.0

Asset retirement obligations as of the end of the period, including current portion
$
233.3