Fair Value Measurements Fair Value Measurements (Estimated Fair Value of Other Financial Assets and Liabilities) (Details) $ in Thousands	Mar. 31, 2020 USD ($)
3.0% Convertible Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, interest rate, stated percentage	3.00%
2.5% Convertible Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, interest rate, stated percentage	2.50%
3.25% Convertible Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, interest rate, stated percentage	3.25%
Convertible Debt \| 3.0% Convertible Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, interest rate, stated percentage	3.00%
Convertible Debt \| 2.5% Convertible Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, interest rate, stated percentage	2.50%
Convertible Debt \| 3.25% Convertible Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, interest rate, stated percentage	3.25%
Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable from third parties (included in other receivables and other assets)	$ 1,127
Investments, at cost, in 50% or less owned companies (included in other assets)	4,201
Long-term debt, including current portion	298,767
Estimate of Fair Value Measurement \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable from third parties (included in other receivables and other assets)	0
Long-term debt, including current portion	0
Estimate of Fair Value Measurement \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable from third parties (included in other receivables and other assets)	1,127
Long-term debt, including current portion	279,349
Estimate of Fair Value Measurement \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable from third parties (included in other receivables and other assets)	0
Long-term debt, including current portion	$ 0

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

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-Publisher FASB
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-Topic 825
-SubTopic 10
-Section 50
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