Segment Reporting The Company has three operating segments, Pharmacy Services, Retail/LTC and Health Care Benefits, as well as a Corporate/Other segment. The Companys segments maintain separate financial information, and the Companys chief operating decision maker (the CODM) evaluates the segments operating results on a regular basis in deciding how to allocate resources among the segments and in assessing segment performance. The CODM evaluates the performance of the Companys segments based on adjusted operating income, which is defined as operating income (GAAP measure) excluding the impact of amortization of intangible assets and other items, if any, that neither relate to the ordinary course of the Companys business nor reflect the Companys underlying business performance. See the reconciliations of operating income (GAAP measure) to adjusted operating income below for further context regarding the items excluded from operating income in determining adjusted operating income. The Company uses adjusted operating income as its principal measure of segment performance as it enhances the Companys ability to compare past financial performance with current performance and analyze underlying business performance and trends. Non-GAAP financial measures the Company discloses, such as consolidated adjusted operating income, should not be considered a substitute for, or superior to, financial measures determined or calculated in accordance with GAAP. The following is a reconciliation of financial measures of the Companys segments to the consolidated totals: In millions Pharmacy Services (1) Retail/ LTC Health Care Benefits Corporate/ Other Intersegment Eliminations Consolidated Totals Three Months Ended September 30, 2020 Revenues from external customers $ 33,492 $ 14,770 $ 18,557 $ 33 $  $ 66,852 Intersegment revenues 2,219 7,955 20  (10,194)  Net investment income   121 83  204 Total revenues 35,711 22,725 18,698 116 (10,194) 67,056 Adjusted operating income (loss) 1,619 1,412 1,080 (303) (186) 3,622 September 30, 2019 Revenues from external customers $ 33,680 $ 13,805 $ 17,027 $ 35 $  $ 64,547 Intersegment revenues 2,338 7,661 8  (10,007)  Net investment income   146 117  263 Total revenues 36,018 21,466 17,181 152 (10,007) 64,810 Adjusted operating income (loss) 1,439 1,516 1,423 (252) (179) 3,947 Nine Months Ended September 30, 2020 Revenues from external customers $ 98,233 $ 44,314 $ 55,972 $ 83 $  $ 198,602 Intersegment revenues 7,350 22,822 51  (30,223)  Net investment income   341 209  550 Total revenues 105,583 67,136 56,364 292 (30,223) 199,152 Adjusted operating income (loss) 4,127 4,371 6,035 (931) (539) 13,063 September 30, 2019 Revenues from external customers $ 95,494 $ 41,536 $ 51,976 $ 76 $  $ 189,082 Intersegment revenues 8,924 22,492 20  (31,436)  Net investment income   458 347  805 Total revenues 104,418 64,028 52,454 423 (31,436) 189,887 Adjusted operating income (loss) 3,682 4,674 4,423 (685) (521) 11,573 _____________________________________________ (1) Total revenues of the Pharmacy Services segment include approximately $2.5 billion and $2.7 billion of retail co-payments for the three months ended September 30, 2020 and 2019, respectively, and $8.5 billion and $8.9 billion of retail co-payments for the nine months ended September 30, 2020 and 2019, respectively. The following are reconciliations of consolidated operating income to adjusted operating income for the three and nine months ended September 30, 2020 and 2019: Three Months Ended September 30, Nine Months Ended September 30, In millions 2020 2019 2020 2019 Operating income (GAAP measure) $ 3,249 $ 2,928 $ 11,387 $ 8,950 Amortization of intangible assets (1) 587 607 1,751 1,822 Acquisition-related integration costs (2) 57 111 196 365 (Gain) loss on divestiture of subsidiary (3) (271) 205 (271) 205 Store rationalization charges (4)  96  231 Adjusted operating income $ 3,622 $ 3,947 $ 13,063 $ 11,573 _____________________________________________ (1) The Companys acquisition activities have resulted in the recognition of intangible assets as required under the acquisition method of accounting which consist primarily of trademarks, customer contracts/relationships, covenants not to compete, technology, provider networks and value of business acquired. Definite-lived intangible assets are amortized over their estimated useful lives and are tested for impairment when events indicate that the carrying value may not be recoverable. The amortization of intangible assets is reflected in the Companys unaudited GAAP condensed consolidated statements of operations in operating expenses within each segment. Although intangible assets contribute to the Companys revenue generation, the amortization of intangible assets does not directly relate to the underwriting of the Companys insurance products, the services performed for the Companys customers or the sale of the Companys products or services. Additionally, intangible asset amortization expense typically fluctuates based on the size and timing of the Companys acquisition activity. Accordingly, the Company believes excluding the amortization of intangible assets enhances the Companys and investors ability to compare the Companys past financial performance with its current performance and to analyze underlying business performance and trends. Intangible asset amortization excluded from the related non-GAAP financial measure represents the entire amount recorded within the Companys GAAP financial statements, and the revenue generated by the associated intangible assets has not been excluded from the related non-GAAP financial measure. Intangible asset amortization is excluded from the related non-GAAP financial measure because the amortization, unlike the related revenue, is not affected by operations of any particular period unless an intangible asset becomes impaired or the estimated useful life of an intangible asset is revised. (2) During the three and nine months ended September 30, 2020 and 2019, acquisition-related integration costs relate to the Aetna Acquisition. The acquisition-related integration costs are reflected in the Companys unaudited GAAP condensed consolidated statements of operations in operating expenses within the Corporate/Other segment. (3) During the three and nine months ended September 30, 2020, the gain on divestiture of subsidiary represents the pre-tax gain on the sale of the Workers Compensation business, which the Company sold on July 31, 2020 for approximately $850 million. The gain on divestiture is reflected as a reduction in operating expenses in the Companys unaudited GAAP condensed consolidated statements of operations within the Health Care Benefits segment. During the three and nine months ended September 30, 2019, the loss on divestiture of subsidiary represents the pre-tax loss on the sale of Onofre, which occurred on July 1, 2019. The loss on divestiture primarily relates to the elimination of the cumulative translation adjustment from accumulated other comprehensive income and is reflected in operating expenses in the Companys unaudited GAAP condensed consolidated statements of operations within the Retail/LTC segment. (4)During the three and nine months ended September 30, 2019, the store rationalization charges relate to the planned closure of 22 underperforming retail pharmacy stores in the first quarter of 2020. During the nine months ended September 30, 2019, the store rationalization charges also relate to the planned closure of 46 underperforming retail pharmacy stores in the second quarter of 2019. The store rationalization charges primarily relate to operating lease right-of-use asset impairment charges and are reflected in the Companys unaudited GAAP condensed consolidated statements of operations in operating expenses within the Retail/LTC segment.