Revenue is measured based on the consideration specified in a contract with a customer. The Partnership recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. Included in “Accounts receivable, net” are $4.1 million and $2.2 million of receivables from contracts with customers as of March 31, 2020, and December 31, 2019, respectively.

Significant changes in the contract asset balance during the period were as follows, and there were no contract liabilities as of March 31, 2020, and December 31, 2019 (in thousands):



Contract assets, December 31, 2019	$	2,765
Revenue recognized from changes in estimates of variable consideration	4
Transferred to receivables from contract assets	(408		)
Contract assets, March 31, 2020	$	2,361

The contract assets in the table above represent rights to consideration for timber deeds transferred to the customer and are related primarily to the Funds Timber segment. These contracts provide the customer the legal right to harvest timber on a designated portion of the Funds’ or Partnership’s property. The value of a timber deed contract is determined based on the estimated timber volume by tree species multiplied by the contracted price. The contract consideration is considered variable because the timber volume by species is an estimate until the harvest is completed. The contract assets are transferred to receivables when the rights to consideration become due under the contract. Customers may harvest the timber at their discretion, within a time period and operational parameters stated in the contract.

The following is a description of principal activities, separated by reportable segments, from which the Partnership generates its revenue.

Partnership Timber and Funds Timber

Log sale revenue in these two segments is recognized when control is transferred, and title and risk of loss passes to the customer, which typically occurs when logs are delivered to the customer. Revenue in these two segments is earned primarily from the harvest and sale of logs from the Partnership’s and Funds’ timberland. Other revenue in these segments is generated from the sale of rights to harvest timber (timber deed sales), commercial thinning, ground leases for cellular communication towers, royalties from gravel mines and quarries, and land use permits. Timber deed sales are generally structured so that the customer pays a contracted price per volume, measured in thousands of board feet (MBF), and revenue is recognized when control is transferred to the customer, which generally occurs on the effective date of the contract. Commercial thinning consists of the selective cutting of timber stands that have not yet reached optimal harvest age. However, this timber does have some commercial value and revenue is based on the volume harvested. Royalty revenue from gravel mines and quarries is recognized monthly based on the quantity of material extracted.

The following table presents log sale and other revenue for the Partnership Timber and Funds Timber segments:



(in thousands)	Quarter ended March 31,
	2020		2019
Partnership Timber
Log sale revenue	$	9,861	$	14,722
Timber deed sale revenue	1,638		—
Other revenue	577		449
Total revenue	$	12,076	$	15,171

Funds Timber
Log sale revenue	$	11,999	$	8,860
Timber deed sale revenue	4		—
Other revenue	47		580
Total revenue	$	12,050	$	9,440

Timberland Investment Management (TIM)

Fee revenue generated by the TIM segment for managing the Funds includes fixed components related to invested capital and acres under management, and a variable component related to harvest volume from the Funds’ tree farms. These fees, which represent an expense in the Funds Timber segment, are eliminated in consolidation. The TIM segment occasionally earns revenue from providing timberland management-related consulting services to third-parties and recognizes such revenue as the related services are provided.

Real Estate

The Real Estate segment’s activities consist of investing in and later selling improved properties, holding properties for later development and sale, and managing commercial properties. Revenue is generated primarily from sales of land, sales of development rights, known as conservation easements (CE’s), sales of unimproved land from the Partnership’s timberland portfolio, and residential and commercial rents. Revenue on real estate sales is recorded on the date the sale closes. When a real estate transaction is closed with obligations to complete infrastructure or other construction, the portion of the total contract allocated to the post-closing obligations may be recognized over time as that work is performed, provided the customer either simultaneously receives and consumes the benefits as we perform under the contract, our performance creates or enhances the asset controlled by the customer, or we do not create an asset with an alternative use to the customer and we have an enforceable right to payment for the performance completed. Progress towards the satisfaction of our performance obligations is generally measured based on costs incurred relative to the total cost expected to be incurred for the performance obligations.

The following table breaks down revenue for the Real Estate segment:



(in thousands)	Quarter ended March 31,
	2020		2019

Sale of unimproved land	$	—	$	22
Rentals and other	259		409
Total revenue	$	259	$	431