Asset Retirement Obligations (Tables)
 9 Months Ended
Sep. 30, 2015
Asset Retirement Obligation [Abstract]  
Changes In Company's Liability For Asset Retirement Obligations
(in millions)
2015
 
2014
 
 
 
Predecessor
Balance as of January 1,
$
23.2

 
$
26.3

Noncontributed net parent investment adjustments(1)
(0.4
)
 
—

Accretion expense
0.9

 
1.1

Additions
0.4

 
2.0

Settlements
—

 
—

Change in estimated cash flows
(1.6
)
 
(0.2
)
Balance as of September 30,
$
22.5

 
$
29.2


(1) Reflects the removal of amounts related to Crossroads Pipeline Company, which was included in the Predecessor but was not contributed to the Partnership.