Business segment data The Company's reportable segments are those that are based on the Company's method of internal reporting, which generally segregates the strategic business units due to differences in products, services and regulation. The internal reporting of these operating segments is defined based on the reporting and review process used by the Company's chief executive officer. The vast majority of the Company's operations are located within the United States. The electric segment generates, transmits and distributes electricity in Montana, North Dakota, South Dakota and Wyoming. The natural gas distribution segment distributes natural gas in those states, as well as in Idaho, Minnesota, Oregon and Washington. These operations also supply related value-added services. The pipeline and midstream segment provides natural gas transportation, underground storage and gathering services through regulated and nonregulated pipeline systems primarily in the Rocky Mountain and northern Great Plains regions of the United States. This segment also provides cathodic protection and other energy-related services. The construction materials and contracting segment mines, processes and sells construction aggregates (crushed stone, sand and gravel); produces and sells asphalt mix; and supplies ready-mixed concrete. This segment focuses on vertical integration of its contracting services with its construction materials to support the aggregate based product lines including aggregate placement, asphalt and concrete paving, and site development and grading. Although not common to all locations, other products include the sale of cement, liquid asphalt for various commercial and roadway applications, various finished concrete products and other building materials and related contracting services. This segment operates in the central, southern and western United States and Alaska and Hawaii. The construction services segment provides inside and outside specialty contracting services. Its outside services include design, construction and maintenance of overhead and underground electrical distribution and transmission lines, substations, external lighting, traffic signalization, and gas pipelines, as well as utility excavation and the manufacture and distribution of transmission line construction equipment. Its inside services include design, construction and maintenance of electrical and communication wiring and infrastructure, fire suppression systems, and mechanical piping and services. This segment also constructs and maintains renewable energy projects. These specialty contracting services are provided to utilities and large manufacturing, commercial, industrial, institutional and government customers. The Other category includes the activities of Centennial Capital, which insures various types of risks as a captive insurer for certain of the Company's subsidiaries. The function of the captive insurer is to fund the self-insured layers of the insured Company's general liability, automobile liability, pollution liability and other coverages. Centennial Capital also owns certain real and personal property. In addition, the Other category includes certain assets, liabilities and tax adjustments of the holding company primarily associated with the corporate functions and certain general and administrative costs (reflected in operation and maintenance expense) and interest expense which were previously allocated to the refining business and Fidelity that do not meet the criteria for income (loss) from discontinued operations. The Other category also includes Centennial Resources' former investment in Brazil. Discontinued operations include the results and supporting activities of Dakota Prairie Refining and Fidelity other than certain general and administrative costs and interest expense as described above. For more information on discontinued operations, see Note 10 . The information below follows the same accounting policies as described in Note 1 of the Company's Notes to Consolidated Financial Statements in the 2018 Annual Report. Information on the Company's segments was as follows: Three Months Ended March 31, 2019 2018 (In thousands) External operating revenues: Regulated operations: Electric $ 92,566 $ 87,404 Natural gas distribution 342,147 332,664 Pipeline and midstream 4,904 4,391 439,617 424,459 Nonregulated operations: Pipeline and midstream 3,709 4,442 Construction materials and contracting 227,113 213,284 Construction services 420,733 334,050 Other 19 58 651,574 551,834 Total external operating revenues $ 1,091,191 $ 976,293 Intersegment operating revenues: Regulated operations: Electric $  $  Natural gas distribution   Pipeline and midstream 23,922 21,735 23,922 21,735 Nonregulated operations: Pipeline and midstream 33 24 Construction materials and contracting 95 101 Construction services 129 11 Other 7,824 2,638 8,081 2,774 Intersegment eliminations (32,003 ) (24,509 ) Total intersegment operating revenues $  $  Three Months Ended March 31, 2019 2018 (In thousands) Operating income (loss): Electric $ 17,987 $ 18,154 Natural gas distribution 50,317 48,540 Pipeline and midstream 9,904 8,168 Construction materials and contracting (41,580 ) (26,309 ) Construction services 27,465 20,634 Other 125 189 Total operating income $ 64,218 $ 69,376 Net income: Regulated operations: Electric $ 15,505 $ 13,084 Natural gas distribution 36,500 32,623 Pipeline and midstream 7,004 5,459 59,009 51,166 Nonregulated operations: Pipeline and midstream (163 ) (179 ) Construction materials and contracting (34,449 ) (23,521 ) Construction services 20,024 15,090 Other (3,332 ) (596 ) (17,920 ) (9,206 ) Income from continuing operations 41,089 41,960 Income (loss) from discontinued operations, net of tax (163 ) 477 Net income $ 40,926 $ 42,437