KOSMOS ENERGY LTD. Notes to Consolidated Financial Statements (Continued) 8. Debt (Continued) the respective amounts of the obligations under the Indenture and the amount of obligations under the Corporate Revolver. The Guarantees are not secured. At December 31, 2017, the estimated repayments of debt during the five years and thereafter are as follows: Payments Due by Year Total 2018 2019 2020 2021 2022 Thereafter (In thousands) Principal debt repayments(1) . . . . . . . . . . $1,325,000 $— $200,377 $404,971 $719,652 $— $— (1) Includes the scheduled principal maturities for the $525.0 million aggregate principal amount of Senior Notes issued in August 2014 and April 2015 and the Facility. The scheduled maturities of debt related to the Facility are based on the level of borrowings and the estimated future available borrowing base as of December 31, 2017. Any increases or decreases in the level of borrowings or increases or decreases in the available borrowing base would impact the scheduled maturities of debt during the next five years and thereafter. As of December 31, 2017, there were no borrowings under the Corporate Revolver. Interest and other financing costs, net Interest and other financing costs, net incurred during the period comprised of the following: Years Ended December 31, 2017 2016 2015 (In thousands) Interest expense . . . . . . . . . . . . . . . . . . . . . . . . . . $ 92,687 $ 89,029 $ 74,897 Amortization—deferred financing costs . . . . . . . . . . 10,204 10,204 10,324 Loss on extinguishment of debt . . . . . . . . . . . . . . . — — 165 Capitalized interest . . . . . . . . . . . . . . . . . . . . . . . . (30,282) (59,803) (52,392) Deferred interest . . . . . . . . . . . . . . . . . . . . . . . . . . 2,577 (581) 1,770 Interest income . . . . . . . . . . . . . . . . . . . . . . . . . . . (3,422) (1,954) (844) Other, net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,831 7,252 3,289 Interest and other financing costs, net . . . . . . . . . $ 77,595 $ 44,147 $ 37,209 9. Derivative Financial Instruments We use financial derivative contracts to manage exposures to commodity price and interest rate fluctuations. We do not hold or issue derivative financial instruments for trading purposes. We manage market and counterparty credit risk in accordance with our policies and guidelines. In accordance with these policies and guidelines, our management determines the appropriate timing and extent of derivative transactions. We have included an estimate of nonperformance risk in the fair value measurement of our derivative contracts as required by ASC 820—Fair Value Measurements and Disclosures. 132