Income Taxes Deferred tax assets and liabilties (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Abstract]
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts	$ 258	$ 262
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities	6,353	3,892
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	126	178
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Self Insurance	14,283	15,054
Deferred Tax Assets Operating Loss Carryforwards - State	0	2,618
Deferred Tax Assets Operating Loss Carryforwards - Federal	0	8,793
Unrecognized tax benefit	1,037	1,052
Deferred Tax Assets, Other	221	3
Deferred Tax Assets, Gross	22,278	31,852
Deferred Tax Assets, Valuation Allowance	0	0
Deferred Tax Assets, Net	22,278	31,852
Deferred Tax Liabilities, Property, Plant and Equipment	(98,355)	(101,843)
Deferred Tax Liabilities, Goodwill and Intangible Assets	(18,959)	(15,939)
Deferred Tax Liabilities, Prepaid Expenses	(804)	(1,762)
Deferred Income Tax Liabilities	(118,118)	(119,544)
Deferred Tax Liabilities, Net	$ (95,840)	$ (87,692)