Asset Retirement Obligations (Tables)
 9 Months Ended
Sep. 30, 2016
Asset Retirement Obligation [Abstract]  
Changes In Company's Liability For Asset Retirement Obligations
(in millions)
2016
 
2015
Balance as of January 1,
$
25.3

 
$
23.2

Noncontributed net parent investment adjustments(1)
—

 
(0.4
)
Accretion expense
0.8

 
0.9

Additions
—

 
0.4

Settlements
—

 
—

Change in estimated cash flows
(3.6
)
 
(1.6
)
Balance as of September 30,
$
22.5

 
$
22.5


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