Related Party Transactions - Additional Information (Details)				3 Months Ended		12 Months Ended
	Apr. 14, 2020 USD ($)	Jan. 15, 2020	Apr. 01, 2019 USD ($) gal	Mar. 25, 2020 USD ($)	Dec. 31, 2018 USD ($) Store	Dec. 31, 2020 USD ($) Store Property Site $ / gal	Dec. 31, 2019 USD ($) Store Property	Dec. 31, 2018 USD ($) Store Property	Jan. 01, 2020 gal	Oct. 29, 2019 USD ($)
Related Party Transaction [Line Items]
Rental income						$ 83,233,000	$ 90,139,000	$ 85,642,000
Accounts receivable from related parties						931,000	4,299,000
Accounts payable to related parties						5,379,000	431,000
Incentive distribution						133,000	533,000	1,579,000
Cost of services						1,720,196,000	1,994,792,000	2,273,122,000
Lease expense						35,362,000	28,557,000
Accounts receivable from related parties						931,000	4,299,000
Income from CST Fuel Supply equity interests						$ 3,202,000	$ 14,768,000	$ 14,948,000
Number of properties sold | Property						33	8	11
Contributions from parent company								$ 6,306,000
Properties Disposed Upon FTC's Requirement [Member]
Related Party Transaction [Line Items]
Number of properties sold | Property						9
General and Administrative Expenses [Member]
Related Party Transaction [Line Items]
Lease expense						$ 1,081,000	$ 685,000
CST Brands Inc. [Member]
Related Party Transaction [Line Items]
Fuel purchase commitments of fixed markup on cost per gallon | $ / gal						0.05
Topper Group Omnibus Agreement [Member]
Related Party Transaction [Line Items]
Partnership agreement effective date		Jan. 01, 2020
Cost and expenses incurred						$ 38,400,000
Wholesale Fuel Supply Contracts/Rights [Member] | CST Brands Inc. [Member]
Related Party Transaction [Line Items]
Equity method investment, ownership percentage						17.50%
Income from CST Fuel Supply equity interests						$ 3,200,000	14,800,000	$ 14,900,000
Transitional Omnibus Agreement [Member] | CST Fuel Supply Exchange [Member]
Related Party Transaction [Line Items]
Reduction of operating expenses				$ 500,000
DMS [Member]
Related Party Transaction [Line Items]
Accounts receivable from related parties							$ 4,100,000
Decrease in rental income			$ 500,000
Fuel purchase agreement reduced per gallon | gal			0.01
Additional fuel purchase agreement reduced per gallon | gal									0.005
Number of remaining fuel deliveries covered by fuel supply agreement | Site						85
Number of Stores | Store					43		12	43
Write off of deferred rent income charges							$ 600,000	$ 2,400,000
Accounts payable to related parties					$ 3,800,000			3,800,000
Accounts receivable from related parties							4,100,000
DMS [Member] | Fuel Sales Transaction [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties						$ 27,127,000	142,236,000	241,151,000
DMS [Member] | Retail and Wholesale Acquisition [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	$ 0
Rental income	$ 0
Topper And Entities [Member]
Related Party Transaction [Line Items]
Rental income						21,000,000.0	300,000	300,000
Accounts receivable from related parties						700,000
Accounts payable to related parties						$ 100,000	100,000
Date of fuel supply to related parties						Apr. 14, 2020
Rent expense						$ 6,600,000	1,100,000	1,000,000.0
Cost of services						600,000	1,000,000.0	1,800,000
Accounts receivable from related parties						700,000
Topper Group [Member]
Related Party Transaction [Line Items]
Cost and expenses incurred						200,000
Incentive distribution						100,000
Dividends cash						37,100,000	16,000,000.0	16,600,000
Lease expense						100,000
Topper Group [Member] | Topper Group Omnibus Agreement [Member]
Related Party Transaction [Line Items]
Accounts payable to related parties						3,700,000
Right of termination prior written notice period		180 days
The General Partner [Member] | Topper Group Omnibus Agreement [Member]
Related Party Transaction [Line Items]
Right of termination prior written notice period		60 days
Topper And Entities [Member]
Related Party Transaction [Line Items]
Accounts payable to related parties						1,500,000
Merchandise costs						14,400,000
CST Brands Inc. [Member]
Related Party Transaction [Line Items]
Rent expense						1,100,000	700,000	700,000
Company Affiliated with a Member of the Board [Member]
Related Party Transaction [Line Items]
Cost of services related to public relations and website consulting						$ 100,000	100,000	100,000
Circle K Stores Inc. [Member]
Related Party Transaction [Line Items]
Number of Stores | Store						45
Incentive distribution							500,000	1,600,000
Dividends cash							15,700,000	16,200,000
Number of retail sites leased to related party | Store						11
Lessor leasing arrangements, operating leases, initial term						10 years
Amounts payable to fuel purchases and freight commissions to related parties							13,900,000
Circle K Stores Inc. [Member] | Properties Disposed Upon FTC's Requirement [Member]
Related Party Transaction [Line Items]
Contributions from parent company					$ 6,300,000
Circle K Stores Inc. [Member] | Fuel Sales Transaction [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties						$ 97,040,000	153,055,000	162,974,000
Accounts receivable from related parties						2,100,000	3,100,000
Accounts receivable from related parties						2,100,000	3,100,000
Circle K Stores Inc. [Member] | Transitional Omnibus Agreement and Circle K Omnibus Agreement [Member]
Related Party Transaction [Line Items]
Cost and expenses incurred							11,600,000	11,800,000
Circle K Stores Inc. [Member] | Omnibus Agreement [Member] | General and Administrative Expenses [Member]
Related Party Transaction [Line Items]
Severance, benefit, and retention costs							100,000	800,000
Circle K Stores Inc. [Member] | Transitional Omnibus Agreement [Member]
Related Party Transaction [Line Items]
Accounts payable to related parties						4,600,000	11,500,000
Circle K Stores Inc. [Member] | Jet-Pep Assets Acquisition [Member]
Related Party Transaction [Line Items]
Purchases from related party						$ 40,100,000	263,500,000	191,000,000.0
Circle K Stores Inc. [Member] | Amended and Restated Omnibus Agreement [Member]
Related Party Transaction [Line Items]
Account payable settlement by parties										$ 183,000
Couche-Tard [Member]
Related Party Transaction [Line Items]
Commission on transportation costs							$ 900,000	$ 500,000