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Fair Value of Financial Instruments
9 Months Ended
Sep. 30, 2018
Fair Value Disclosures [Abstract]  
Fair Value of Financial Instruments
Fair Value of Financial Instruments

The following table presents the carrying amounts and estimated fair values of our long-term debt, excluding capital lease and other obligations, as well as the input level used to determine the fair values indicated below:
 
 
 
September 30, 2018
 
December 31, 2017
 
Input
Level
 
Carrying
Amount
 
Fair
Value
 
Carrying
Amount
 
Fair
Value
 
 
 
(Dollars in millions)
Liabilities—Long-term debt, excluding capital lease and other obligations
2
 
$
35,702

 
35,750

 
36,835

 
36,402