Income Taxes - Deferred taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deferred Income Tax Assets
Accounts receivable allowances	$ 432	$ 406
Environmental liability	11,087	12,041
Asset retirement obligation	2,813	2,769
Deferred financing obligation	9,924	10,247
Lease liability	50,152	38,400
Other	1,108	3,619
Federal net operating loss carryforwards	2,610	5,521
State net operating loss carryforwards	300	433
Tax credit carryforward	1,727	1,709
Interest expense carryforwards	18,570	16,493
Total deferred tax assets, gross	98,723	91,638
Valuation allowance	(5,781)	(5,323)	$ (4,728)	$ (4,231)
Total deferred tax assets, net	92,942	86,315
Deferred Income Tax Liabilities
Property and equipment	(84,961)	(95,823)
Land	(16,543)	(17,675)
Right of use assets	(48,718)	(36,797)
Basis difference in SPR joint venture	(5,168)	(4,929)
Intangible assets	(1,100)
Total deferred tax liabilities	(156,490)	(155,224)
Net deferred tax liabilities	$ (63,548)	$ (68,909)