Acquisitions Divestitures (Details) $ in Thousands		3 Months Ended	12 Months Ended
		Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts Receivable, before Allowance for Credit Loss, Current		$ 50,899	$ 61,675	$ 50,899
Proceeds from the sale of discontinued operations				23,100
Depreciation and amortization				477	$ 582
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		(336,876)	(368,743)	(336,876)
Disposal Group, Including Discontinued Operation, Operating Income (Loss)			(204)	(1,578)	(223)
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax			809	(1,875)	(517)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax			200	7,344	0
Discontinued Operation, Tax Effect of Discontinued Operation			(153)	(1,416)	129
Gain Loss From Discontinued Operations			856	4,053	(388)
Disposal Group, Including Discontinued Operation, Assets, Current		134,826	136,431	134,826
Deferred Income Tax Expense (Benefit)	[1]		$ 24,200	23,904	20,914
Number of Disposal Transactions			4
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax		$ 5,402	$ 170	5,402
PESCO [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax				7,500
Discontinued Operations, Held-for-sale or Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Revenue			26	161,289	258,713
Disposal Group, Including Discontinued Operation, Costs of Goods Sold			0	157,646	252,111
Disposal Group, Including Discontinued Operation, Operating Expense			230	5,221	6,825
Disposal Group, Including Discontinued Operation, Interest Income			1,013
Disposal Group, Including Discontinued Operation, Interest Expense				(297)	(294)
Discontinued Operation, Tax Effect of Discontinued Operation			(153)	(1,416)	129
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Combination, Working Capital			8,000
Capital Expenditure, Discontinued Operations				0	115
Deferred Income Tax Expense (Benefit)				(125)	1,088
Gain from a settlement				(2,161)	$ 5,002
PESCO [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Intra-Entity Amounts, Discontinued Operation after Disposal, Revenue			$ 19,800	$ 31,500

[1] (1) Includes $4.9 million, $4.7 million, and $3.5 million of deferred state income taxes for the years 2020, 2019 and 2018, respectively.