Note 14. Fair Value Measurements and Derivatives In measuring the fair value of our assets and liabilities, we use market data or assumptions that we believe market  participants would use in pricing an asset or liability including assumptions about risk when appropriate. Our valuation  techniques include a combination of observable and unobservable inputs. Fair value measurements on a recurring basis  — Assets and liabilities that are carried in our balance sheet at fair value are as  follows: During January 2014, we sold our interest in a payment-in-kind callable note to a third party for  $75. Accordingly, we  reclassified the note to current assets and, with observable market value readily available, we reduced the unrealized gain and  transferred the note from Level 3 to Level 2 at December 31, 2013. Fair value of financial instruments  — The financial instruments that are not carried in our balance sheet at fair value are as  follows: The fair value of our senior notes is estimated based upon a market approach (Level 2) while the fair value of our other  indebtedness is based upon an income approach (Level 2). See Note 13 for additional information about financing  arrangements. 73 Fair Value Measurements Using Quoted Prices in Active Markets Significant Inputs Observable Significant Inputs Unobservable December 31, 2014 Total (Level 1) (Level 2) (Level 3) Marketable securities - current asset $ 169 $ 72 $ 97 $ — Currency forward contracts - current asset 2 2 Currency forward contracts - current liability 11 11 Currency swaps - current asset — — Currency swaps - current liability 9 9 December 31, 2013 Notes receivable - current asset $ 75 $ — $ 75 $ — Marketable securities - current asset 110 33 77 Currency forward contracts - current asset 3 3 Currency forward contracts - current liability 2 2 Currency swaps - noncurrent asset 2 2 Currency swaps - noncurrent liability 2 2 Changes in Level 3 recurring fair value measurements  — Notes receivable, including current portion 2014 2013 2012 Beginning of period $ — $ 129 $ 116 Accretion of value (interest income) 11 14 Payment received and other (61) (1) Unrealized loss (OCI) (4) Transfer out (to Level 2) (75) End of period $ — $ — $ 129 2014 2013 Carrying Value Fair Value Carrying Value Fair Value Senior notes $ 1,580 $ 1,643 $ 1,500 $ 1,567 Other indebtedness 79 77 99 98 Total $ 1,659 $ 1,720 $ 1,599 $ 1,665