value, less costs to sell, in accordance with the guidance. Any such adjustment to the carrying value is recorded as an impairment loss.
We assess the carrying value of our investments in hotel properties whenever events or changes in circumstances indicate that the carrying amounts may not be recoverable. The recoverability is measured by comparing the carrying amount to the estimated undiscounted future cash flows expected to be generated from the operations and the eventual disposition of the hotel properties over the estimated hold period, which take into account current market conditions and our intent with respect to holding or disposing of the hotel properties. If our analysis indicates that the carrying value is not recoverable on an undiscounted cash flow basis, we will recognize an impairment loss for the amount by which the carrying value exceeds the fair value. The fair value is determined through various valuation techniques, including internally developed discounted cash flow models, comparable market transactions, third-party appraisals, the net sales proceeds from pending offers, or the net sales proceeds from transactions that closed subsequent to the end of the reporting period. The use of projected future cash flows is based on assumptions that are consistent with a market participant’s future expectations for the travel industry and the economy in general, including discount rates, terminal capitalization rates, average daily rates, occupancy rates, operating expenses and capital expenditures, and our intent with respect to holding or disposing of the underlying hotel properties.
Our revenues consist of room revenue, food and beverage revenue, and revenue from other hotel operating departments (such as parking fees, golf, pool and other resort fees, gift shop sales and other guest service fees). A performance obligation is a promise in a contract to transfer a distinct good or service to the customer. The contract's transaction price is allocated to each distinct performance obligation and recognized as revenue when the performance obligation is satisfied. Our contracts generally have a single performance obligation, such as renting a hotel room to a customer, or providing food and beverage to a customer, or providing a hotel property-related good or service to a customer. Our performance obligations are generally satisfied at a point in time.
We allocate revenue to the performance obligation based on its relative standalone selling price. We determine the standalone selling price based on the price we charge each customer for the use or consumption of the promised good or service.
We recognize revenue when control of the promised good or service is transferred to the customer, in an amount that reflects the consideration we expect to receive in exchange for the promised good or service. The revenue is recorded net of any sales and occupancy taxes collected from the customer. All rebates or discounts are recorded as a reduction to revenue, and there are no material contingent obligations with respect to rebates and discounts offered by the hotel properties.
Hotel and other receivables are recognized on the consolidated balance sheets when we have provided a good or service to the customer and we are waiting for the customer to submit consideration to us. Advance deposits and deferred revenue are recognized on the consolidated balance sheets when cash payments are received prior to the satisfaction of a performance obligation. Advance deposits and deferred revenue consist of amounts that are refundable and non-refundable to the customer. The advance deposits and deferred revenue are recognized as revenue in the consolidated statements of operations and comprehensive income when we satisfy our performance obligation to the customer.
We record an allowance for doubtful accounts based on our best estimate of the amount of probable credit losses in the existing accounts receivable portfolio. We recognize increases to the allowance for doubtful accounts as bad debt expense. The allowance for doubtful accounts is calculated as a percentage of the aged accounts receivable based on our historical collection activity and our understanding of the circumstances related to a specific receivable.
Item 7A. Quantitative and Qualitative Disclosures About Market Risk
Market risk includes the risks that arise from changes in interest rates, equity prices and other market changes that affect market sensitive instruments. Our primary market risk exposure is to changes in interest rates on our variable rate debt. As of December 31, 2018, we had approximately $1.6 billion of total variable rate debt outstanding (or 71.3% of total indebtedness) with a weighted-average interest rate of 3.44% per annum. After taking into consideration the effect of interest rate swaps, $192.0 million (or 8.8% of total indebtedness) was subject to variable rates. As of December 31, 2018, if market interest rates on our variable rate debt not subject to interest rate swaps were to increase by 1.00%, or 100 basis points, interest expense would decrease future earnings and cash flows by approximately $1.9 million annually, taking into account our existing contractual hedging arrangements.