14. Segments The following table presents the Companys operations by reportable segment. The Company is managed through three reportable segments, Technology &amp; Analytics Solutions, Research &amp; Development Solutions and Contract Sales &amp; Medical Solutions . Technology &amp; Analytics Solutions provides mission-critical information, technology solutions and real-world insights and services to the Companys life sciences customers. Research &amp; Development Solutions, which primarily serves biopharmaceutical customers, provides outsourced clinical research and clinical trial related services. Contract Sales &amp; Medical Solutions provides health care provider (including contract sales) and patient engagement services to both biopharmaceutical customers and the broader healthcare market. Certain costs are not allocated to the Companys segments and are reported as general corporate and unallocated expenses. These costs primarily consist of stock-based compensation and expenses related to integration activities and acquisitions. The Company also does not allocate depreciation and amortization or impairment charges to its segments. Prior period segment results have been recast to conform to changes to management reporting in 2019. The recast impacts the allocation of selling, general and administrative expenses for 2018. Asset information by segment is not presented, as this measure is not used by the chief operating decision maker to assess the Companys performance. The Companys reportable segment information is presented below: Three Months Ended September 30, Nine Months Ended September 30, (in millions) 2019 2018 2019 2018 Revenues Technology &amp; Analytics Solutions $ 1,095 $ 1,014 $ 3,272 $ 3,010 Research &amp; Development Solutions 1,466 1,382 4,317 4,097 Contract Sales &amp; Medical Solutions 208 198 604 617 Total revenues 2,769 2,594 8,193 7,724 Costs of revenue, exclusive of depreciation and amortization Technology &amp; Analytics Solutions 667 589 1,956 1,718 Research &amp; Development Solutions 1,007 921 2,924 2,765 Contract Sales &amp; Medical Solutions 178 168 519 521 Total costs of revenue 1,852 1,678 5,399 5,004 Selling, general and administrative expenses Technology &amp; Analytics Solutions 167 190 539 558 Research &amp; Development Solutions 172 171 529 519 Contract Sales &amp; Medical Solutions 15 16 45 51 General corporate and unallocated 41 52 137 145 Total selling, general and administrative expenses 395 429 1,250 1,273 Segment profit Technology &amp; Analytics Solutions 261 235 777 734 Research &amp; Development Solutions 287 290 864 813 Contract Sales &amp; Medical Solutions 15 14 40 45 Total segment profit 563 539 1,681 1,592 General corporate and unallocated (41 ) (52 ) (137 ) (145 ) Depreciation and amortization (299 ) (283 ) (888 ) (847 ) Restructuring costs (19 ) (23 ) (45 ) (66 ) Total income from operations $ 204 $ 181 $ 611 $ 534