BUSINESS SEGMENT INFORMATION As of December 31, 2019 , Apache is engaged in exploration and production (Upstream) activities across three operating segments: Egypt, North Sea, and the U.S. Apache also has exploration interests in Suriname and other international locations that may, over time, result in reportable discoveries and development opportunities. Apaches Upstream business explores for, develops, and produces natural gas, crude oil and natural gas liquids. During 2018, Apache established a new reporting segment for its U.S. midstream business separate from its upstream oil and gas development activities. The midstream business is operated by Altus, which owns, develops, and operates a midstream energy asset network in the Permian Basin of West Texas, anchored by midstream service contracts to Apaches production from its Alpine High resource play. Additionally, Altus owns equity interests in a total of four Permian Basin pipelines that will access various points along the Texas Gulf Coast, providing it with fully integrated, wellhead-to-water connectivity. Financial information for each segment is presented below: Egypt (1) North Sea U.S. Altus Midstream Intersegment Eliminations &amp; Other Total (2) Upstream (In millions) 2019 Oil revenues $ 1,969 $ 1,163 $ 2,098 $  $  $ 5,230 Natural gas revenues 295 90 293   678 Natural gas liquids revenues 12 23 372   407 Oil and gas production revenues 2,276 1,276 2,763   6,315 Midstream service affiliate revenues    136 (136 )  Operating Expenses: Lease operating expenses 484 320 645  (2 ) 1,447 Gathering, processing, and transmission 40 45 299 56 (134 ) 306 Taxes other than income   194 13  207 Exploration 100 2 688  15 805 Depreciation, depletion, and amortization 708 366 1,566 40  2,680 Asset retirement obligation accretion  76 29 2  107 Impairments   1,648 1,301  2,949 1,332 809 5,069 1,412 (121 ) 8,501 Operating Income (Loss) $ 944 $ 467 $ (2,306 ) $ (1,276 ) $ (15 ) (2,186 ) Other Income (Expense): Gain on divestitures, net 43 Other (3) 53 General and administrative (406 ) Transaction, reorganization, and separation (50 ) Financing costs, net (462 ) Loss Before Income Taxes $ (3,008 ) Net Property and Equipment $ 2,573 $ 1,956 $ 9,385 $ 206 $ 38 $ 14,158 Total Assets (5) $ 3,700 $ 2,473 $ 10,388 $ 1,479 $ 67 $ 18,107 Additions to Net Property and Equipment $ 454 $ 183 $ 1,696 $ 308 $ 93 $ 2,734 Egypt (1) North Sea U.S. Altus Midstream Intersegment Eliminations &amp; Other Total (2) Upstream (In millions) 2018 Oil revenues $ 2,396 $ 1,179 $ 2,271 $  $  $ 5,846 Natural gas revenues 339 122 458   919 Natural gas liquids revenues 13 20 550   583 Oil and gas production revenues 2,748 1,321 3,279   7,348 Midstream service affiliate revenues    77 (77 )  Operating Expenses: Lease operating expenses 428 341 670   1,439 Gathering, processing, and transmission 47 42 282 54 (77 ) 348 Taxes other than income   207 8  215 Exploration 88 192 219  4 503 Depreciation, depletion, and amortization 745 375 1,266 19  2,405 Asset retirement obligation accretion  75 32 1  108 Impairments 63 10 438   511 1,371 1,035 3,114 82 (73 ) 5,529 Operating Income (Loss) $ 1,377 $ 286 $ 165 $ (5 ) $ (4 ) 1,819 Other Income (Expense): Gain on divestitures, net 23 Other (3) 53 General and administrative (431 ) Transaction, reorganization, and separation (28 ) Financing costs, net (478 ) Income Before Income Taxes $ 958 Net Property and Equipment $ 2,856 $ 2,148 $ 12,145 $ 1,227 $ 45 $ 18,421 Total Assets (5) $ 4,260 $ 2,456 $ 12,962 $ 1,857 $ 47 $ 21,582 Additions to Net Property and Equipment $ 594 $ 223 $ 2,544 $ 545 $ 8 $ 3,914 Egypt North Sea Canada (4) U.S. Altus Midstream Intersegment Eliminations &amp; Other Total (2) Upstream (In millions) 2017 Oil revenues $ 1,901 $ 971 $ 110 $ 1,616 $  $  $ 4,598 Natural gas revenues 395 92 104 368   959 Natural gas liquids revenues 11 15 17 287   330 Oil and gas production revenues 2,307 1,078 231 2,271   5,887 Midstream service affiliate revenues     15 (15 )  Operating Expenses: Lease operating expenses 362 335 103 584   1,384 Gathering, processing, and transmission 44 30 34 86 16 (15 ) 195 Taxes other than income  (14 ) 12 153   151 Exploration 62 86 11 363  27 549 Depreciation, depletion, and amortization 758 446 76 994 6  2,280 Asset retirement obligation accretion  72 27 31   130 Impairments  8     8 1,226 963 263 2,211 22 12 4,697 Operating Income (Loss) $ 1,081 $ 115 $ (32 ) $ 60 $ (7 ) $ (27 ) 1,190 Other Income (Expense): Gain on divestitures, net 627 Other (3) (91 ) General and administrative (395 ) Transaction, reorganization, and separation (16 ) Financing costs, net (397 ) Income Before Income Taxes $ 918 Net Property and Equipment $ 3,099 $ 2,553 $  $ 11,370 $ 700 $ 37 $ 17,759 Total Assets (5) $ 4,658 $ 2,977 $  $ 13,522 $ 706 $ 59 $ 21,922 Additions to Net Property and Equipment $ 517 $ 374 $  $ 1,847 $ 550 $ 14 $ 3,302 (1) Includes revenue from non-customers for the years ended 2019 and 2018 of: For the Year Ended December 31, 2019 2018 (In millions) Oil $ 410 $ 592 Natural gas 40 58 Natural gas liquids 1 2 (2) Includes a noncontrolling interest in Egypt for years 2019 , 2018 , and 2017 , and Altus for the years 2019 and 2018 . (3) Included in Other are sales proceeds related to U.S. third-party purchased oil and gas volumes which are determined to be revenue from customers. Proceeds for these volumes totaled $176 million and $357 million for the years ended 2019 and 2018 , respectively. (4) During 2017, Apache completed the sale of its Canadian operations. For more information regarding this divestiture, please refer to Note 2Acquisitions and Divestitures. (5) Intercompany balances are excluded from total assets.