Discontinued Operation (Cash Flow Of Discontinued Operations) (Details) - Pumpco [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Depreciation and amortization	$ 75,077	$ 122,409	$ 111,860
Reduction in value of assets	76,577	417,011	3,765
Payments for capital expenditures	(36,743)	$ (108,094)	(99,544)
Proceeds from sales of assets	$ 1,669		$ 5,262