Revenue Recognition Revenues are recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. For revenue disaggregated by major product line for each reportable segment, see Note 13, Segment Information. Wood Products Segment Our Wood Products segment manufactures EWP, consisting of laminated veneer lumber (LVL), I-joists, and laminated beams, which are structural products used in applications where extra strength and consistent quality are required, such as headers and beams. LVL is also used in the manufacture of I-joists, which are assembled by combining a vertical web of oriented strand board (OSB) with top and bottom LVL or solid wood flanges. In addition, we manufacture structural, appearance, and industrial plywood panels. We also produce ponderosa pine lumber, and particleboard. Our wood products are used primarily in new residential construction, residential repair-and-remodeling markets, and light commercial construction. The majority of our wood products are sold to leading wholesalers (including our Building Materials Distribution segment), home improvement centers, retail lumberyards, and industrial converters. For engineered wood products (EWP), plywood and veneer, lumber, byproducts, particleboard, and other products, we transfer control and recognize a sale when we ship the product from our manufacturing facility to our customer. Control transfers when product is shipped because the customer has legal title, a present obligation to pay, and risk and rewards of ownership. The amount of consideration we receive and revenue we recognize varies with changes in rebates and cash discounts we offer to our customers. See discussion of rebates and cash discounts below. Building Materials Distribution Segment Our Building Materials Distribution segment is a leading national stocking wholesale distributor of building materials. We distribute a broad line of building materials, including EWP; commodity products such as OSB, plywood, and lumber; and general line items such as siding, metal products, insulation, roofing, and composite decking. Except for EWP, we purchase most of these building materials from third-party suppliers and market them primarily to retail lumberyards, home improvement centers, and specialty distributors that then sell the products to the final end customers, who are typically professional builders, independent contractors, and homeowners engaged in residential construction projects. Substantially all of Building Materials Distribution's EWP is sourced from our Wood Products segment. We sell products using two primary distribution methods: warehouse sales and direct sales. Warehouse sales are distributed from our warehouses to our customers. Direct sales are shipped from the manufacturer to the customer without our taking physical inventory possession. We report direct sales on a gross basis, that is, the amounts billed to our customers are recorded as "Sales," and inventory purchased from manufacturers are recorded as "Materials, labor, and other operating expenses (excluding depreciation)." We are the principal of direct sales because we control the inventory before it is transferred to our customers. Our control is evidenced by us being primarily responsible for fulfilling the promise to our customers, taking on inventory risk of returned product, and having discretion in establishing pricing. For warehouse sales, we transfer control and recognize a sale when the customer takes physical possession of the product. Control transfers when the customer takes physical possession of the product because the customer has legal title, a present obligation to pay, and risk and rewards of ownership. For direct sales, we transfer control and recognize a sale when the product is shipped from the manufacturer to the customer. Control transfers when product is shipped because the customer has legal title, a present obligation to pay, and risk and rewards of ownership. The amount of consideration we receive and revenue we recognize varies with changes in customer rebates and cash discounts we offer to our customers. See discussion of rebates and cash discounts below. Rebates and Cash Discounts Rebates are provided to our customers and our customers' customers based on the volume of their purchases, among other factors such as customer loyalty, conversion, and commitment. We provide the rebates to increase the sell-through of our products. Rebates are generally estimated based on the expected amount to be paid and recorded as a decrease in "Sales." At September 30, 2018 , and December 31, 2017 , we had $61.3 million and $45.5 million , respectively, of rebates payable to our customers recorded in "Accrued liabilities, Other" on our Consolidated Balance Sheets. We estimate the expected cash discounts based on an analysis of historical experience and record cash discounts as a decrease in "Sales." We adjust our estimate of revenue at the earlier of when the probability of rebates paid and cash discounts provided changes or when the amounts become fixed. We believe that there will not be significant changes to our estimates of variable consideration. Shipping and Handling Fees for shipping and handling charged to customers for sales transactions are included in "Sales." When control over products has transferred to the customer, we have elected to recognize costs related to shipping and handling as an expense. For our Wood Products segment, costs related to shipping and handling are included in "Materials, labor, and other operating expenses (excluding depreciation)." In our Wood Products segment, we view our shipping and handling costs as a cost of the manufacturing process and the movement of product to our end customers. For our Building Materials Distribution segment, costs related to shipping and handling of $42.8 million and $37.9 million , for the three months ended September 30, 2018 , and 2017 , respectively, and $117.1 million and $101.5 million for the nine months ended September 30, 2018 and 2017 , respectively, are included in "Selling and distribution expenses". In our Building Materials Distribution segment, our activities relate to the purchase and resale of finished product, and excluding shipping and handling costs from Materials, labor, and other operating expenses (excluding depreciation) provides us a clearer view of our operating performance and the effectiveness of our sales and purchasing functions. Other Our payment terms vary by the type of customer and the products offered. The term between invoicing and when payment is due is not significant.