The Combined Guarantor Subsidiaries adopted ASC 606 (which includes ASU 2014-09 and all related subsequent amendments) on January 1, 2018 and applied the guidance to contracts that were not complete as of January 1, 2018. Historical amounts for prior periods were not adjusted and will continue to be reported using the guidance in ASC 605, Revenue Recognition .

Sales of real estate assets are accounted for under ASC 610-20, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets , which provides for revenue recognition based on the transfer of control. There should be no change in revenue recognition for sales in which the Com bined Guarantor Subsidiaries ha ve no continuing involvement. ASU 2017-05 addresses revenue recognition related to property sales in which the Com bined Guarantor Subsidiaries ha ve continuing involvement and may require full gain recognition.

The following table presents the Combined Guarantor Subsidiaries' revenues disaggregated by revenue source:

	Year Ended December 31,
	2019		2018
Rental revenues⁽¹⁾	$	277,452	$	311,804
Revenues from contracts with customers (ASC 606):
Operating expense reimbursements ⁽²⁾		4,045		3,914
Marketing revenues ⁽³⁾		2,760		2,673
		6,805		6,587

Other revenues		733		534
Total revenues⁽⁴⁾	$	284,990	$	318,925

Under operating and other agreements with third parties that own anchor or outparcel buildings at the Guarantor Properties and pay no rent, the Combined Guarantor Subsidiaries receive reimbursements for certain operating expenses such as ring road and parking lot maintenance, landscaping and other fees. These arrangements are primarily either set at a fixed rate with rate increases typically every five years or are on a variable (pro rata) basis, typically as a percentage of costs allocated based on square footage or sales. The majority of these contracts have an initial term and one or more extension options, which cumulatively approximate 50 or more years as historically the initial term and any extension options are reasonably certain of being executed by the third party. The standalone selling price of each performance obligation is determined based on the terms of the contract, which typically assign a price to each performance obligation that directly relates to the value the customer receives for the services being provided. Revenue is recognized as services are transferred to the customer. Variable consideration is based on historical experience and is generally recognized over time using the cost-to-cost method of measurement because it most accurately depicts the Combined Guarantor Subsidiaries' performance in satisfying the performance obligation. The cumulative catch-up method is used to recognize any adjustments in variable consideration estimates. Under this method, any adjustment is recognized in the period it is identified.

The Combined Guarantor Subsidiaries earn marketing revenues from advertising and sponsorship agreements. These fees may be for tangible items in which the Combined Guarantor Subsidiaries provide advertising services and create signs and other promotional materials for the tenant or may be arrangements in which the customer sponsors a play area or event and receives specified brand recognition and other benefits over a set period of time. Revenue related to advertising services is recognized as goods and services are provided to the customer. Sponsorship revenue is recognized on a straight-line basis over the time period specified in the contract.

A performance obligation is a promise in a contract to transfer a distinct good or service to a customer. If the contract does not specify the revenue by performance obligation, the Combined Guarantor Subsidiaries allocate the transaction price to each performance obligation based on its relative standalone selling price. Such prices are generally determined using prices charged to customers or using the Combined Guarantor Subsidiaries' expected cost plus margin. Revenue is recognized as the Combined Guarantor Subsidiaries' performance obligations are satisfied over time, as services are provided, or at a point in time, such as leasing a space to earn a commission. Open performance obligations are those in which the Combined Guarantor Subsidiaries have not fully or have partially provided the applicable goods or services to the customer as specified in the contract. If consideration is received in advance of the Combined Guarantor Subsidiaries' performance, including amounts which are refundable, recognition of revenue is deferred until the performance obligation is satisfied or amounts are no longer refundable.

The Combined Guarantor Subsidiaries do not disclose the value of open performance obligations for (1) contracts with an original expected duration of one year or less and (2) contracts for which the Combined Guarantor Subsidiaries recognize revenue at the amount to which they have the right to invoice, which primarily relate to services performed for certain operating expense reimbursements, as described above. Performance obligations related to fixed operating expense reimbursements for certain noncancellable contracts are disclosed below.

The Combined Guarantor Subsidiaries have outstanding performance obligations related to certain noncancellable contracts with customers for which they will receive fixed operating expense reimbursements for providing certain maintenance and other services as described above . As of December 31, 2019, the Combined Guarantor Subsidiaries expect to recognize these amounts as revenue over the following periods:

Performance obligation

Less than

5 years

5-20 years

Over 20

years

Total

Fixed operating expense reimbursements

12,895

23,584

31,712

68,191

The Combined Guarantor Subsidiaries evaluate performance obligations each period and make adjustments to reflect any known additions or cancellations. Performance obligations related to variable consideration, which is based on sales, are constrained.