We measure and analyze our segment performance on the basis of "adjusted operating revenue" and "adjusted operating income" or "adjusted operating loss", which differ from total revenue and income before income tax as presented in our consolidated statements of income due to the exclusion of net realized investment gains and losses and amortization of the cost of reinsurance as well as and certain other items as specified in the reconciliations below. These performance measures are in accordance with GAAP guidance for segment reporting, but they should not be viewed as a substitute for total revenue, income before income tax, or net income.  A reconciliation of total revenue to "adjusted operating revenue" and income before income tax to "adjusted operating income" is as follows: Year Ended December 31 2020 2019 2018 (in millions of dollars) Total Revenue $ 13,162.1  $ 11,998.9  $ 11,598.5  Excluding: Net Realized Investment Gain (Loss) 1,199.1  (23.2) (39.5) Adjusted Operating Revenue $ 11,963.0  $ 12,022.1  $ 11,638.0  Income Before Income Tax $ 964.0  $ 1,382.1  $ 627.8  Excluding: Net Realized Investment Gains and Losses Net Realized Investment Gain Related to Reinsurance Transaction 1,302.3  —  —  Net Realized Investment Loss, Other (103.2) (23.2) (39.5) Total Net Realized Investment Gain (Loss) 1,199.1  (23.2) (39.5) Items Related to Closed Block Individual Disability Reinsurance Transaction Change in Benefit Reserves and Transaction Costs (1,305.5) —  —  Amortization of the Cost of Reinsurance (2.6) —  —  Total Items Related to Closed Block Individual Disability Reinsurance Transaction (1,308.1) —  —  Long-term Care Reserve Increase (151.5) —  (750.8) Group Pension Reserve Increase (17.5) —  —  Costs Related to Organizational Design Update (23.3) —  —  Impairment Loss on ROU Asset (12.7) —  —  Costs Related to Early Retirement of Debt —  (27.3) —  Adjusted Operating Income $ 1,278.0  $ 1,432.6  $ 1,418.1  44