Long-Term Debt (Schedule Of Company's Borrowings) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, gross	$ 386,059	$ 606,092
Portion due within one year	(8,497)	(77,842)
Debt discount included in long-term debt	(28,334)	(23,152)
Debt issuance costs included in long-term debt	(3,100)	(3,593)
Long-term debt, excluding current maturities	346,128	501,505
Convertible Debt \| 3.0% Convertible Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	107,284	230,000
Debt discount included in long-term debt	(7,200)	(22,900)
Debt issuance costs included in long-term debt	(700)	(2,300)
Convertible Debt \| 2.5% Convertible Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	64,455	64,455
Convertible Debt \| 3.25% Convertible Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	117,782	0
Debt discount included in long-term debt	(21,100)
Debt issuance costs included in long-term debt	(1,900)
Senior Notes \| 7.375% Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	0	153,090
Debt discount included in long-term debt		(200)
Debt issuance costs included in long-term debt		(300)
Line of Credit \| SEA-Vista Credit Facility
Debt Instrument [Line Items]
Long-term debt, gross	87,977	135,714
Debt issuance costs included in long-term debt	(400)	(700)
Line of Credit \| ISH Credit Facility
Debt Instrument [Line Items]
Long-term debt, gross	0	12,200
Debt issuance costs included in long-term debt		(100)
Notes Payable, Other Payables
Debt Instrument [Line Items]
Long-term debt, gross	8,561	10,633
Debt issuance costs included in long-term debt	$ (100)	$ (100)

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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