XML 45 R31.htm IDEA: XBRL DOCUMENT v3.3.1.900
Asset Retirement Obligations (Tables)
 12 Months Ended
Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]  
Schedule of Asset Retirement Obligations [Table Text Block]
The following table provides asset retirement obligation activity for the years ended December 31, 2015 and 2014 (dollars in millions):
 
 
2015
 
2014
Asset retirement obligation at January 1
 
$
85

 
$
56

Accretion expense
 
9

 
8

Liabilities assumed in tw telecom acquisition
 
—

 
22

Liabilities settled
 
(8
)
 
(7
)
Revision in estimated cash flows
 
5

 
7

Effect of foreign currency rate change
 
(1
)
 
(1
)
Asset retirement obligation at December 31
 
$
90

 
$
85