2. Revenue

Revenue Disaggregation Table

The following table shows revenues by major product categories, similar to our reportable segment disclosure. Within each product category, contract terms, conditions and economic factors affecting the nature, amount, timing and uncertainty around revenue recognition and cash flows are substantially similar. The commercial markets and selling channels are also similar. Except for an inconsequential amount of revenue for Telecommunications products, our product category revenues are recognized at point in time when control transfers to the customer.

Revenues by product category are as follows (in millions):



	Three Months Ended
	March 31,
	2019		2018
Display products	$	795	$	732

Telecommunication products		1,064		886

Specialty glass products		309		278

Environmental substrate and filter products		351		322

Life science products		239		232

All Other		54		50
	$	2,812	$	2,500

Contract Assets and Liabilities

Contract assets, such as costs to obtain or fulfill contracts, are an insignificant component of Corning’s revenue recognition process. The majority of Corning’s cost of fulfillment as a manufacturer of products is classified as inventory, fixed assets and intangible assets, which are accounted for under the respective guidance for those asset types. Other costs of contract fulfillment are immaterial due to the nature of our products and their respective manufacturing processes.

Contract liabilities include deferred revenues, other advanced payments and customer deposits. Deferred revenue and other advanced payments are not significant to our operations and are classified as part of other current liabilities in our financial statements. Customer deposits are predominately related to Display products and are classified as part of other current liabilities and other long- term liabilities as appropriate, and are disclosed below.

We treat shipping and handling fees as a fulfillment cost and not as a separate performance obligation under the terms of our revenue contracts due to the perfunctory nature of the shipping and handling obligations.

Customer Deposits

As of March 31, 2019 and December 31, 2018, Corning had customer deposits of approximately $1.0 billion. The majority of these represent non-refundable cash deposits for customers to secure rights to an amount of glass produced by Corning under long-term supply agreements. The duration of these long-term supply agreements ranges up to ten years. As glass is shipped to customers, Corning will recognize revenue and issue credit memoranda to reduce the amount of the customer deposit liability, which are applied against customer receivables resulting from the sale of glass. In the three months ended March 31, 2019 and 2018, no credit memoranda were issued. As of March 31, 2019 and December 31, 2018, $907 million and $922 million were recorded as other long-term liabilities, respectively. The remaining $84 million and $54 million, respectively, were classified as other current liabilities.