Basis of Presentation and Policies - Environment, Property, Intangibles, Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Accrual environmental liabilities	$ 0	$ 0
Net capitalized turnaround costs	43,900	23,100
Land held for sale	0	11,800
Deferred taxes on land held for sale		2,800
Impairment losses on goodwill	0	0	$ 0
Impairment loss on intangible asset	$ 0	$ 0	$ 0
Customer Relationships [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	19 years	19 years
Minimum | Developed Technology [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	9 years	9 years
Maximum | Developed Technology [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	15 years	15 years