Dealership Vehicle, Parts and Service Sales. We record revenue when vehicles are delivered and title has passed to the customer, when vehicle service or repair work is completed, and when parts are delivered to our customers. Sales promotions that we offer to customers are accounted for as a reduction of revenues at the time of sale. Rebates and other incentives offered directly to us by manufacturers are recognized as a reduction of cost of sales. Reimbursements of qualified advertising expenses are treated as a reduction of selling, general and administrative expenses. The amounts received under certain manufacturer rebate and incentive programs are based on the attainment of program objectives, and such earnings are recognized either upon the sale of the vehicle for which the award was received, or upon attainment of the particular program goals if not associated with individual vehicles. Taxes collected from customers and remitted to governmental authorities are recorded on a net basis (excluded from revenue). During 2016, 2015, and 2014, we earned $654.9 million, $628.9 million, and $592.5 million, respectively, of rebates, incentives and reimbursements from manufacturers, of which $638.2 million, $611.7 million, and $578.2 million, respectively, was recorded as a reduction of cost of sales. The remaining $16.7 million, $17.2 million, and $14.3 million, was recorded as a reduction of selling, general and administrative expenses during 2016, 2015, and 2014, respectively.
Dealership Finance and Insurance Sales. Subsequent to the sale of a vehicle to a customer, we sell installment sale contracts to various financial institutions on a non-recourse basis (with specified exceptions) to mitigate the risk of default. We receive a commission from the lender equal to either the difference between the interest rate charged to the customer and the interest rate set by the financing institution or a flat fee. We also receive commissions for facilitating the sale of various products to customers, including guaranteed vehicle protection insurance, vehicle theft protection and extended service contracts. These commissions are recorded as revenue at the time the customer enters into the contract. In the case of finance contracts, a customer may prepay or fail to pay their contract, thereby terminating the contract. Customers may also terminate extended service contracts and other insurance products, which are fully paid at purchase, and become eligible for refunds of unused premiums. In these circumstances, a portion of the commissions we received may be charged back based on the terms of the contracts. The revenue we record relating to these transactions is net of an estimate of the amount of chargebacks we will be required to pay. Our estimate is based upon our historical experience with similar contracts, including the impact of refinance and default rates on retail finance contracts and cancellation rates on extended service contracts and other insurance products. Aggregate reserves relating to chargeback activity were $23.5 million and $23.8 million as of December 31, 2016 and 2015, respectively.
Commercial Vehicle Distribution. Revenue from the distribution of vehicles, engines, power systems and parts is recognized at the time of delivery of goods to the retailer or the ultimate customer.
Other indefinite-lived intangible assets are assessed for impairment annually on October 1 and upon the occurrence of an indicator of impairment through a comparison of its carrying amount and estimated fair value. An indicator of impairment exists if the carrying value exceeds its estimated fair value and an impairment loss may be recognized up to that excess. The fair value is determined using a discounted cash flow approach, which includes assumptions about revenue and profitability growth, profit margins, and the cost of capital. We also evaluate in connection with the annual impairment testing whether events and circumstances continue to support our assessment that the other indefinite-lived intangible assets continue to have an indefinite life.
Goodwill impairment is assessed at the reporting unit level annually on October 1 and upon the occurrence of an indicator of impairment. Our operations are organized by management into operating segments by line of business and geography. We have determined that we have four reportable segments as defined in generally accepted accounting principles for segment reporting: (i) Retail Automotive, consisting of our retail automotive dealership operations; (ii) Retail Commercial Truck, consisting of our retail commercial truck dealership operations in the U.S. and Canada; (iii) Other, consisting of our commercial vehicle and power systems distribution operations and other non-automotive consolidated operations; and (iv) Non-Automotive Investments, consisting of our equity method investments in non-automotive operations. We have determined that the dealerships in each of our operating segments within the Retail Automotive reportable segment are components that are aggregated into four geographical reporting units for the purpose of goodwill impairment testing, as they (A) have similar economic characteristics (all are automotive dealerships having similar margins), (B) offer similar products and services (all sell new and used vehicles, service, parts