Fair Value Measurements (Estimated Fair Value Of Other Financial Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
3.0% Convertible Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, stated percentage	3.00%
3.25% Convertible Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, stated percentage	3.25%
Convertible Debt \| 3.0% Convertible Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, stated percentage	3.00%
Convertible Debt \| 3.25% Convertible Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, stated percentage	3.25%
Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable from third parties (included in other receivables and other assets)	$ 2,182	$ 2,647
Investments, at cost, in 50% or less owned companies (included in other assets)	4,300	4,300
Long-term debt, including current portion	354,625	579,347
Estimate of Fair Value Measurement \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable from third parties (included in other receivables and other assets)	0	943
Long-term debt, including current portion	0	0
Estimate of Fair Value Measurement \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable from third parties (included in other receivables and other assets)	2,159	1,642
Long-term debt, including current portion	353,929	596,246
Estimate of Fair Value Measurement \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable from third parties (included in other receivables and other assets)	0	0
Long-term debt, including current portion	$ 0	$ 0

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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