We conduct our business in two segments: 1) the Wholesale segment and 2) the Retail segment. The wholesale segment includes the wholesale distribution of motor fuel to lessee dealers, independent dealers, commission agents, DMS, Circle K and, through September 2019, company operated retail sites. We have exclusive motor fuel distribution contracts with lessee dealers who lease the property from us. We also have exclusive distribution contracts with independent dealers to distribute motor fuel but do not collect rent from the independent dealers. Similar to lessee dealers, we have motor fuel distribution agreements with DMS and Circle K and collect rent from both. The Retail segment includes the retail sale of motor fuel at retail sites operated by commission agents and through September 2019, the sale of convenience merchandise items and the retail sale of motor fuel at company operated retail sites. A commission agent is a retail site where we retain title to the motor fuel inventory and sell it directly to our end user customers. At commission agent retail sites, we manage motor fuel inventory pricing and retain the gross profit on motor fuel sales, less a commission to the agent who operates the retail site. Similar to our Wholesale segment, we also generate revenues through leasing or subleasing real estate in our Retail segment.

Unallocated items consist primarily of general and administrative expenses, depreciation, amortization and accretion expense, gains on dispositions and lease terminations, net, and the elimination of the Retail segment’s intersegment cost of revenues from motor fuel sales against the Wholesale segment’s intersegment revenues from motor fuel sales. The profit in ending inventory generated by the intersegment motor fuel sales is also eliminated. Total assets by segment are not presented as management does not currently assess performance or allocate resources based on that data.

The following table reflects activity related to our reportable segments (in thousands):

	Wholesale		Retail		Unallocated			Consolidated
Year Ended December 31, 2019
Revenues from fuel sales to external customers	$	1,609,547	$	397,474	$	—		$	2,007,021
Intersegment revenues from fuel sales		306,070		—		(306,070	)		—
Revenues from food and merchandise sales		—		49,382		—			49,382
Rent income		81,427		8,712		—			90,139
Other revenue		2,887		—		—			2,887
Total revenues	$	1,999,931	$	455,568	$	(306,070	)	$	2,149,429
Income from CST Fuel Supply equity interests	$	14,768	$	—	$	—		$	14,768
Operating income (loss)^(a)	$	113,299	$	3,189	$	(73,166	)	$	43,322

Year Ended December 31, 2018
Revenues from fuel sales to external customers	$	1,713,227	$	546,061	$	—		$	2,259,288
Intersegment revenues from fuel sales		425,610		—		(425,610	)		—
Revenues from food and merchandise sales		—		97,603		—			97,603
Rent income		77,404		8,238		—			85,642
Other revenue		3,384		—		—			3,384
Total revenues	$	2,219,625	$	651,902	$	(425,610	)	$	2,445,917
Income from CST Fuel Supply equity interests	$	14,948	$	—	$	—		$	14,948
Operating income (loss)	$	117,848	$	8,429	$	(91,265	)	$	35,012

Year Ended December 31, 2017
Revenues from fuel sales to external customers	$	1,521,408	$	380,387	$	—		$	1,901,795
Intersegment revenues from fuel sales		281,561		—		(281,561	)		—
Revenues from food and merchandise sales		—		104,362		—			104,362
Rent income		79,344		6,970		—			86,314
Other revenue		2,356		—		—			2,356
Total revenues	$	1,884,669	$	491,719	$	(281,561	)	$	2,094,827
Income from CST Fuel Supply equity interests	$	14,906	$	—	$	—		$	14,906
Operating income (loss)	$	108,624	$	5,737	$	(81,942	)	$	32,419

(a)

As discussed in Note 2, as a result of the adoption of ASC 842, operating income for 2019 is not comparable to operating income for 2018 and 2017. Most significantly, payments on our previous failed sale-leaseback obligations were characterized as principal and interest expense in periods prior to 2019. Starting in 2019, these payments are characterized as rent expense and thus reduce operating income. These payments for the Wholesale and Retail segments amounted to approximately $6.7 million and $0.5 million for 2019.

Receivables relating to the revenue streams above are as follows (in thousands):

Performance obligations are satisfied as fuel is delivered to the customer. Many of our contracts with our customers include minimum purchase volumes measured on a monthly basis, although such revenue is not material. Receivables from fuel are recognized on a per-gallon rate and are generally collected within 10 days of delivery.

The balance of unamortized costs incurred to obtain certain contracts with customers was $6.5 million and $5.7 million at December 31, 2019 and 2018, respectively. Amortization of such costs is recorded against operating revenues and amounted to $1.0 million, $0.9 million and $0.6 million for 2019, 2018 and 2017, respectively

Receivables from rent and other lease-related charges are generally collected at the beginning of the month.

When we convert company owned retail sites from our Retail segment to lessee dealers in our Wholesale segment, we no longer generate revenues from the retail sale of motor fuel or merchandise at these stores subsequent to the date of conversion and we no longer incur retail operating expenses related to these retail sites. However, we continue to supply these retail sites with motor fuel on a wholesale basis pursuant to the fuel supply contract with the lessee dealer. Further, we continue to own or lease the property and earn rental income under lease/sublease agreements with the lessee dealers under triple net leases. The lessee dealer owns all motor fuel and convenience merchandise and retains all gross profit on such operating activities.

In June 2019, we entered into master fuel supply and master lease agreements with Applegreen. During the third quarter of 2019, we dealerized 46 company operated Upper Midwest sites. The master fuel supply and master lease agreements have an initial 10-year term with four 5-year renewal options. Base rent generally increases by 1.5% annually, including during the renewal options. Applegreen has the right to sever up to 10 specifically identified sites, for which notice must be provided prior to the end of the first year, and the effective date will be after the second year. Applegreen has the right to sever up to eight of the remaining 36 sites with proper notice. We have committed to making certain EMV upgrades at these 46 sites totaling approximately $2.2 million by October 1, 2020.

In connection with the conversion of these company operated sites in our Retail segment to lessee dealer sites in our Wholesale segment, we recognized a $0.5 million loss on sale of inventory to Applegreen, classified within the loss on dispositions and lease terminations, net line item of the statement of income. As further discussed in Note 9, we also reassigned $4.5 million of goodwill from the Retail segment to the Wholesale segment.

As a result of this transition, we have not had any company operated sites since September 30, 2019. See Note 25 for information regarding the acquisition of retail and wholesale assets from the Topper Group and certain other parties.