Asset Retirement Obligations (Tables)
 12 Months Ended
Dec. 31, 2015
Asset Retirement Obligation [Abstract]  
Changes In 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
1.2

 
1.5

Additions
4.1

 
2.2

Settlements
—

 
(6.6
)
Change in estimated cash flows
(2.8
)
 
(0.2
)
Balance as of December 31,
$
25.3

 
$
23.2


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