Interest Expense Fair Value Disclosures Total interest expense, including interest expense related to our convertible notes, consisted of the following (in millions): The following table shows the carrying amount, which is net of unamortized premium, discount and debt issuance costs, and estimated fair value of our debt (in millions): (1) Includes 2021 SPL Senior Notes, 2022 SPL Senior Notes, 2023 SPL Senior Notes, 2024 SPL Senior Notes, 2025 SPL Senior Notes, 2026 SPL Senior Notes, 2027 SPL Senior Notes, 2028 SPL Senior Notes, 2025 CQP Senior Notes, 2026 CQP Senior Notes, 2024 CCH Senior Notes, 2025 CCH Senior Notes and 2027 CCH Senior Notes. The Level 2 estimated fair value was based on quotes obtained from broker-dealers or market makers of these senior notes and other similar instruments. (2) The Level 3 estimated fair value was calculated based on inputs that are observable in the market or that could be derived from, or corroborated with, observable market data, including our stock price and interest rates based on debt issued by parties with comparable credit ratings to us and inputs that are not observable in the market.  (3) Includes SPL Working Capital Facility, CQP Credit Facilities, CCH Credit Facility, CCH Working Capital Facility, Cheniere Revolving Credit Facility and Cheniere Marketing trade finance facilities. The Level 3 estimated fair value approximates the principal amount because the interest rates are variable and reflective of market rates and the debt may be repaid, in full or in part, at any time without penalty.  (4) The Level 1 estimated fair value was based on unadjusted quoted prices in active markets for identical liabilities that we had the ability to access at the measurement date. 93 December 31, 2018 December 31, 2017 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Senior notes (1) $ 19,466 $ 19,901 $ 18,350 $ 20,075 2037 SPL Senior Notes (2) 791 817 790 871 Credit facilities (3) 5,294 5,294 3,574 3,574 2021 Cheniere Convertible Unsecured Notes (2) 1,126 1,236 1,040 1,136 2025 CCH HoldCo II Convertible Senior Notes (2) 1,432 1,612 1,273 1,535 2045 Cheniere Convertible Senior Notes (4) 310 431 309 447 Year Ended December 31, 2018 2017 2016 Interest cost on convertible notes: Interest per contractual rate $ 237 $ 219 $ 202 Amortization of debt discount 35 29 31 Amortization of debt issuance costs 9 7 5 Total interest cost related to convertible notes 281 255 238 Interest cost on capital lease 1 — — Interest cost on debt excluding capital lease and convertible notes 1,396 1,271 1,063 Total interest cost 1,678 1,526 1,301 Capitalized interest (803) (779) (813) Total interest expense, net $ 875 $ 747 $ 488 CHENIERE ENERGY, INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—CONTINUED