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Summary of Significant Accounting Policies (Tables)
 12 Months Ended
Dec. 31, 2017
Summary of Significant Accounting Policies  
Schedule of changes in the asset retirement obligation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Years ended December 31,

 

(Millions of dollars)

    

2017

    

2016

 

Beginning balance

 

$

19

 

$

18

 

Accretion expense

 

 

 2

 

 

 1

 

Liability for additional lagoons placed in service

 

 

 1

 

 

 —

 

Ending balance

 

$

22

 

$

19

 

 

Schedule of amounts paid for interest and income taxes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Years ended December 31,

 

(Millions of dollars)

    

2017

    

2016

    

2015

 

Interest, net of interest capitalized

 

$

30

 

$

29

 

$

17

 

Income taxes, net of refunds

 

 

32

 

 

31

 

 

60