and requires amortization of the excess net gain or loss that exceeds the corridor over the average remaining service periods of active plan participants. For our closed plans or plans that are primarily inactive, the average remaining life expectancy of all plan participants (including retirees) is used. If our actuarial losses significantly exceed this corridor in the future, significant incremental pension and postretirement costs could result. As of year-end 2019, the deferred losses of several of our Canadian plans, as well as those in our U.K. plan, and the deferred gains of our U.S. plan, exceeded the 10% corridor. 

The assumed health care cost trend rates represent the rates at which health care costs are assumed to increase and are based on actuarial input and consideration of historical and expected experience. We use these trends as a significant assumption in determining our postretirement benefit obligation and related costs. Changes in our projections of future health care costs due to general economic conditions and those specific to health care will impact this trend rate. An increase in the trend rate would increase our obligation and expense of our postretirement health care plan. We believe that our health care cost trend rate assumptions are appropriate; however, significant changes in our assumptions may materially affect our postretirement benefit obligations and related costs. As of December 31, 2019, the health care trend rates used were ranging ratably from 6.25% in 2020 to 3.57% in 2040, consistent with our health care trend rates ranging ratably from 6.5% in 2019 to 4.5% in 2037 used as of December 31, 2018. See Part II—Item 8 Financial Statements and Supplementary Data, Note 15, "Employee Retirement Plans and Postretirement Benefits"  for further information. 

## Contingencies, Environmental and Litigation Reserves 

Contingencies, environmental and litigation reserves are recorded, when probable, using our best estimate of loss. This estimate, involving significant judgment, is based on an evaluation of the range of loss related to such matters and where the amount and range can be reasonably estimated. These matters are generally resolved over a number of years and only when one or more future events occur or fail to occur. Following our initial determination, we regularly reassess and revise the potential liability related to any pending matters as new information becomes available. Unless capitalization is allowed or required by U.S. GAAP, environmental and legal costs are expensed when incurred. We disclose pending loss contingencies when the loss is deemed reasonably possible, which requires significant judgment. As a result of the inherent uncertainty of these matters, the ultimate conclusion and actual cost of settlement may materially differ from our estimates. We recognize contingent gains upon the determination that realization is assured beyond a reasonable doubt, regardless of the perceived probability of a favorable outcome prior to achieving that assurance. In the instance of gain contingencies resulting from favorable litigation, due to the numerous uncertainties inherent in a legal proceeding, gain contingencies resulting from legal settlements are not recognized in income until cash or other forms of payment are received. If significant and probable, we disclose as appropriate. 

See Part I—Item 3 Legal Proceedings and Part II—Item 8 Financial Statements and Supplementary Data, Note 18, "Commitments and Contingencies"  for a discussion of our contingencies, environmental and litigation reserves as of December 31, 2019. 

## Goodwill and Intangible Asset Valuation 

Goodwill is allocated to the reporting unit in which the business that created the goodwill resides. A reporting unit is an operating segment, or a business unit one level below that operating segment, for which discrete financial information is prepared and regularly reviewed by segment management. As of the date of completion of our 2019 impairment testing, the operations in each of the specific regions within our U.S., Canada, Europe and International segments are components based on the availability of discrete financial information and the regular review by segment management. Therefore, the components within each respective segment must be evaluated for aggregation to determine if the components have similar economic characteristics. As a result, in certain cases, we have aggregated components, within an operating segment, into one reporting unit if the specific aggregation criteria under U.S. GAAP is met. Specifically, we have concluded that the components within the U.S., Canada and Europe segment each meet the criteria as having similar economic characteristics and therefore have aggregated these components into the U.S., Canada and Europe reporting units, respectively. Therefore, the U.S., Canada and Europe reporting units are consistent with our operating segments. However, for our India business, the reporting unit is one level below the International operating segment. Any change to the conclusion of our reporting units or the aggregation of components within our reporting units, including potential changes resulting from our revitalization plan, could result in a different outcome to our annual impairment test. As of the date of our annual impairment test, our significant indefinite-lived intangible assets included the Coors and Miller brand families in the U.S., the Coors Light  distribution rights in Canada, and the Carling and Staropramen  brands in Europe. 

We evaluate the carrying value of our goodwill and indefinite-lived intangible assets for impairment at least annually or when an interim triggering event occurs that would indicate that impairment may have taken place. We identified a triggering event requiring an interim impairment assessment of the goodwill within our Canada and India reporting units at the end of the third quarter of 2019. Our annual impairment test of indefinite-lived intangible assets was performed as of October 1, the first day of the last fiscal quarter. We evaluate our other definite-lived intangible assets for impairment when evidence exists that 

