Table of Contents Beginning January 1, 2018, we adopted new accounting guidance issued by the FASB resulting in the unrealized gains and losses arising from the revaluation of these equity securities to be included in Other income (expense) in Statement 1. Prior to January 1, 2018, the unrealized gains and losses arising from revaluation of the available-for-sale equity securities and the Real Estate Investment Trust were included, net of applicable deferred income taxes, in equity (Accumulated other comprehensive income (loss) in Statement 3). See Note 1J for additional information. The cost basis and fair value of debt and equity securities with unrealized gains and losses included in equity (Accumulated other comprehensive income (loss) in Statement 3) were as follows: $^{1 }$Beginning January 1, 2018, the unrealized gains and losses arising from the revaluation of the equity securities are included in Other income (expense) in Statement 1. See Note 1J for additional information. December 31, 2018 December 31, 2017 (Millions of dollars) Cost Basis Unrealized Pretax Net Gains (Losses) Fair Value Cost Basis Unrealized Pretax Net Gains (Losses) Fair Value Government debt U.S. treasury bonds $ 9 $ — $ 9 $ 10 $ — $ 10 Other U.S. and non-U.S. government bonds 42 — 42 42 — 42 Corporate bonds Corporate bonds 735 (15) 720 585 (1) 584 Asset-backed securities 63 — 63 67 — 67 Mortgage-backed debt securities U.S. governmental agency 301 (4) 297 265 (4) 261 Residential 7 — 7 8 — 8 Commercial 14 (1) 13 17 — 17 Total debt securities $ 1,171 $ (20) $ 1,151 $ 994 $ (5) $ 989 Equity securities  1 Large capitalization value 287 (3) 284 Real estate investment trust (REIT) 104 6 110 Smaller company growth 40 16 56 Total $ 431 $ 19 $ 450 111