SEGMENT INFORMATION Our reportable segments, which are the same as our operating segments, are organized based on the nature of markets and customers. We report our operating results through our four operating segments that consist of similar products and services within each segment as described below. OILFIELD SERVICES (OFS) Oilfield Services provides products and services for onshore and offshore operations across the lifecycle of a well, ranging from drilling, evaluation, completion, production and intervention. Products and services include diamond and tri-cone drill bits, drilling services, including directional drilling technology, measurement while drilling &amp; logging while drilling, downhole completion tools and systems, wellbore intervention tools and services, wireline services, drilling and completions fluids, oilfield and industrial chemicals, pressure pumping, and artificial lift technologies, including electrical submersible pumps. OILFIELD EQUIPMENT (OFE) Oilfield Equipment provides a broad portfolio of products and services required to facilitate the safe and reliable flow of hydrocarbons from the subsea wellhead to the surface. Products and services include pressure control equipment and services, subsea production systems and services, drilling equipment, and flexible pipeline systems. Oilfield Equipment designs and manufactures onshore and offshore drilling and production systems and equipment for floating production platforms and provides a full range of services related to onshore and offshore drilling activities. TURBOMACHINERY &amp; PROCESS SOLUTIONS (TPS) Turbomachinery &amp; Process Solutions provides equipment and related services for mechanical-drive, compression and power-generation applications across the oil and gas industry as well as products and services to serve the downstream segments of the industry including refining, petrochemical, distributed gas, flow and process control and other industrial applications. The Turbomachinery &amp; Process Solutions portfolio includes drivers (aero-derivative gas turbines, heavy-duty gas turbines and synchronous and induction electric motors), compressors (centrifugal and axial, direct drive high speed, integrated, subsea compressors, turbo expanders and reciprocating), turn-key solutions (industrial modules and waste heat recovery), pumps, valves, and compressed natural gas (CNG) and small-scale liquefied natural gas (LNG) solutions used primarily for shale oil and gas field development. DIGITAL SOLUTIONS (DS) Digital Solutions provides equipment, software, and services for a wide range of industries, including oil &amp; gas, power generation, aerospace, metals, and transportation. The offerings include sensor-based process measurement, non-destructive testing and inspection, turbine, generator and plant controls and condition monitoring, as well as pipeline integrity solutions. SEGMENT RESULTS Segment revenue and profit are determined based on the internal performance measures used by the Company to assess the performance of each segment in a financial period. Summarized financial information is shown in the following tables. Consistent accounting policies have been applied by all segments within the Company, for all reporting periods. Three Months Ended September 30, Nine Months Ended September 30, Segment revenue 2020 2019 2020 2019 Oilfield Services $ 2,308 $ 3,348 $ 7,858 $ 9,597 Oilfield Equipment 726 728 2,133 2,156 Turbomachinery &amp; Process Solutions 1,513 1,197 3,759 3,904 Digital Solutions 503 609 1,460 1,833 Total $ 5,049 $ 5,882 $ 15,210 $ 17,490 The performance of our operating segments is evaluated based on segment operating income (loss), which is defined as income (loss) before income taxes before the following: net interest expense, net other non-operating loss, corporate expenses, restructuring, impairment and other charges, inventory impairments, separation related costs, goodwill impairments and certain gains and losses not allocated to the operating segments. Three Months Ended September 30, Nine Months Ended September 30, Segment income (loss) before income taxes 2020 2019 2020 2019 Oilfield Services $ 93 $ 274 $ 345 $ 683 Oilfield Equipment 19 14 (4) 40 Turbomachinery &amp; Process Solutions 191 161 473 414 Digital Solutions 46 82 117 234 Total segment 349 531 931 1,370 Corporate (115) (109) (353) (314) Inventory impairment (1) (42)  (218)  Goodwill impairment   (14,773)  Restructuring, impairment and other (209) (71) (1,637) (183) Separation related (32) (54) (110) (128) Other non-operating loss, net (149) (14) (367) (124) Interest expense, net (66) (59) (195) (174) Total $ (264) $ 224 $ (16,722) $ 446 (1) Charges for inventory impairments are predominantly reported in the "Cost of goods sold" caption of the condensed consolidated statements of income (loss). The following table presents total assets by segment: Segment assets September 30, 2020 December 31, 2019 Oilfield Services $ 15,963 $ 30,611 Oilfield Equipment 3,687 7,645 Turbomachinery &amp; Process Solutions 8,727 8,365 Digital Solutions 3,890 3,983 Total segment 32,267 50,604 Corporate and eliminations (1) 5,072 2,765 Total $ 37,339 $ 53,369 (1) Corporate and eliminations in total segment assets includes adjustments of intercompany investments and receivables that are reflected within the total assets of the four reportable segments.