Other long-term liabilities are comprised of the following obligations:


	December 31, 2023		December 31, 2022
Deferred revenue	$	248.8	$	198.8
Asset retirement obligations		103.0		97.9
Operating lease liabilities		56.5		28.6
Other liabilities		6.8		15.9
Total other long-term liabilities	$	415.1	$	341.2

Deferred revenue as of December 31, 2023 and 2022 was $248.8 million and $198.8 million, respectively, which includes $129.0 million of payments received from Vitol Americas Corp. (“Vitol”) (formerly known as Noble Americas Corp.), a subsidiary of Vitol US Holding Co., in 2016, 2017, and 2018 as part of an agreement (the “Splitter Agreement”) related to the construction and operation of a crude oil and condensate splitter. In December 2018, Vitol elected to terminate the Splitter Agreement. The Splitter Agreement provides that the first three annual payments are ours if Vitol elects to terminate, which Vitol disputes. The timing of revenue recognition related to the Splitter Agreement deferred revenue is dependent on the outcome of current litigation with Vitol. See Note 18 - Contingencies for more information.

Deferred revenue includes nonmonetary consideration received in a 2015 amendment (the “gas contract amendment”) to a gas gathering and processing agreement. We measured the estimated fair value of the gathering assets transferred to us using significant other observable inputs representative of a Level 2 fair value measurement. In December 2017, we received monetary consideration to further amend the terms of the gas gathering and processing agreement. The deferred revenue related to these amendments is being recognized through the end of the agreement’s term in 2035.

Deferred revenue also includes contributions in aid of construction received from customers for which revenue is recognized over the expected contract term.

For the years ended December 31, 2023, 2022 and 2021, we recognized $17.4 million, $7.5 million and $3.9 million of revenue for these transactions, respectively.

The following table shows the components of deferred revenue:


	December 31, 2023		December 31, 2022
Splitter agreement	$	129.0	$	129.0
Gas contract amendment		29.8		32.3
Contributions in aid of construction (1)		86.4		31.7
Other		3.6		5.8
Total deferred revenue	$	248.8	$	198.8

(1)

Increase in contributions in aid of construction was due to additions of deferred revenue in West Texas and Badlands.

The following table shows the changes in deferred revenue:


	2023			2022
Balance at beginning of period	$	198.8		$	171.8
Additions		67.4			34.5
Revenue recognized		(17.4	)		(7.5	)
Balance at end of period	$	248.8		$	198.8

Our ARO primarily relate to certain gas gathering pipelines and processing facilities and NGL pipelines. The changes in our ARO are as follows:


	2023			2022
Beginning of period	$	97.9		$	72.1
Additions (1)		—			20.2
Accretion expense		5.9			4.8
Change in cash flow estimate		4.9			0.8
Retirements		(5.7	)		—
End of period	$	103.0		$	97.9

(1)

Amount reflects additions of ARO in 2022 related to the Delaware Basin Acquisition.