Our product revenue is recognized when control of the goods is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods. In most cases, control is transferred when products are shipped. We recognize the vast majority of our service revenue as the services are provided. Many of our check supply contracts with financial institutions provide for rebates on certain products. We record these rebates as reductions of revenue and as accrued liabilities on our consolidated balance sheets when the related revenue is recognized. Many of our financial institution contracts also require prepaid product discounts in the form of upfront cash payments we make to our financial institution clients. These prepaid product discounts are included in other non-current assets in our consolidated balance sheets and are amortized as reductions of revenue, generally on the straight-line basis, over the contract term. Sales tax collected concurrent with revenue-producing activities is excluded from revenue. Amounts billed to customers for shipping and handlin g are included in revenue, while the related shipping and handling costs are reflected in cost of products. We have elected the practical expedient that allows us to account for shipping and handling activities that occur after the customer has obtained control of a good as a fulfillment cost, and we accrue costs of shipping and handling when the related revenue is recognized. As part of our Financial Services rewards, incentive and loyalty programs, we receive payments from consumers or our clients for the products and services provided, including hotel stays, gift cards and merchandise, such as apparel, electronics and clothing. This revenue is recorded net of the related fulfillment costs. Certain of our contracts for data-driven marketing solutions and treasury management outsourcing services within Financial Services have variable consideration that is contingent on either the success of the marketing campaign ("pay-for-performance") or the volume of outsourcing services provided. We recognize revenue for estimated variable consideration as services are provided based on the most likely amount to be realized. Revenue is recognized to the extent that it is probable that a significant reversal of revenue will not occur when the contingency is resolved. Estimates regarding the recognition of variable consideration are updated each quarter. Typically, the amount of consideration for these contracts is finalized within 3 months, although pricing under certain of our outsourcing contracts may be based on annual volume commitments. Revenue recognized from these contracts was approximately $100,000 in 2017. Under the new standard, we have accelerated the recognition of a portion of this variable consideration. Certain of our contracts for treasury management solutions result from the sale of bundled arrangements that may include hardware, software and professional services, as well as customization and modification of software, and specify the timing of customer billings over the course of the contract. Revenue for these contracts is recognized using a cost-based input method that depicts the transfer of services to the customer. The transaction price is allocated to each performance obligation based on its relative standalone selling price. We generally determine standalone selling prices based on the prices charged to customers or using expected cost plus margin. When the revenue recognized for uncompleted contracts exceeds the amount of customer billings and the right to receive the consideration is conditional, a contract asset is recorded. These amounts are included in revenue in excess of billings on the consolidated balance sheets and totaled $20,508 as of September 30, 2018 and $9,665 as of January 1, 2018. Additionally, we record an asset for unbilled receivables when the revenue recognized has not been billed to customers in accordance with contractually stated billing terms and the right to receive the consideration is unconditional. These assets are also included in revenue in excess of earnings on our consolidated balance sheets and totaled $13,227 as of September 30, 2018 and $7,674 as of January 1, 2018. When the amount of customer billings for uncompleted contracts exceeds the revenue recognized, a contract liability is reflected in our consolidated balance sheets within accrued liabilities. The amount included in accrued liabilities was $1,563 as of September 30, 2018 and $2,233 as of December 31, 2017. At times, a financial institution client may terminate its check supply contract with us prior to the end of the contract term. In many cases, the financial institution is contractually required to remit a contract termination payment. Such payments are recorded as revenue when the termination agreement is executed, provided that we have no further performance obligations and collection of the funds is assured. If we have further performance obligations following the execution of a contract termination agreement, we record the related revenue over the remaining service period. Our payment terms vary by type of customer and the products or services offered. The time period between invoicing and when payment is due is not significant. For certain products, services and customer types, we require payment before the products or services are delivered to the customer. When a customer pays in advance, primarily for treasury management solutions and web hosting services, we defer the revenue and recognize it as the services are performed, generally over a period of less than 1 year. Deferred revenue is included in accrued liabilities and other non-current liabilities in our consolidated balance sheets. The decrease of $8,263 in deferred revenue for the nine months ended September 30, 2018 was driven primarily by the recognition of $39,488 of revenue that was included in deferred revenue as of December 31, 2017 , partially offset by cash payments received in advance of satisfying our performance obligations. In addition to the amounts included in deferred revenue, we will recognize revenue in future periods related to remaining performance obligations for certain of our data-driven marketing and treasury management solutions. Generally, these contracts have terms of 1 year or less and many have terms of 3 months or less. The amount of revenue related to these unsatisfied performance obligations is not significant to our annual consolidated revenue. The new guidance requires that certain costs incurred to obtain contracts be recognized as assets and amortized consistent with the transfer of goods or services to the customer. As such, we are now deferring sales commissions related to obtaining check supply and treasury management solution contracts within Financial Services. These amounts are included in other non-current assets and are amortized as selling, general and administrative (SG&amp;A) expense. Amortization of these amounts on the straight-line basis approximates the timing of the transfer of goods or services to the customer. Generally, these amounts are being amortized over periods of 3 to 6 years. We elected the practical expedient allowing us to expense sales commissions as incurred when the amortization period would have been 1 year or less.