Other Accrued Expense (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Schedule of Other Accrued Expense [Line Items]
Asset Retirement Obligation, Current	$ 33,875
Other accrued expenses	85,520	$ 81,715
Current Liabilities
Schedule of Other Accrued Expense [Line Items]
Accrued Employee Benefits, Current	24,106	23,304
Asset Retirement Obligation, Current	33,875	33,933
Accrued Environmental Loss Contingencies, Current	11,992	10,139
Operating and Finance Lease Liability, Current	7,532	7,986
Other Accrued Liabilities	8,015	6,353
Other accrued expenses	$ 85,520	$ 81,715