Commitments and Contingencies Environmental Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Environmental remediation obligations [Member]
Environmental remediation obligation, minimum	$ 24,100
Environmental remediation obligation, maximum	30,700
Accrual for environmental loss contingencies	26,866	$ 28,895	$ 30,276	$ 29,741
Deductions	(2,799)	(2,977)	(2,232)
Charged to costs and expense	770	$ 1,596	$ 2,767
Combined Manufacturing Sites [Member] | Manufactured Gas Plants [Member]
Accrual for environmental loss contingencies	22,100
Aberdeen South Dakota Site [Member] | Manufactured Gas Plants [Member]
Accrual for environmental loss contingencies	8,100
Environmental remediation obligation, to be incurred during next 5 years	$ 3,000