Other Accrued Expense (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Schedule of Other Accrued Expense [Line Items]
Asset Retirement Obligation, Current	$ 33,792
Other accrued expenses	77,559	$ 81,715
Current Liabilities
Schedule of Other Accrued Expense [Line Items]
Accrued Employee Benefits, Current	19,311	23,304
Asset Retirement Obligation, Current	33,792	33,933
Accrued Environmental Loss Contingencies, Current	10,365	10,139
Operating and Finance Lease Liability, Current	7,803	7,986
Other Accrued Liabilities	6,288	6,353
Other accrued expenses	$ 77,559	$ 81,715