Note 4 - Long-term Debt - Long-term Debt Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Long-term Debt, Gross	$ 2,570,026
Total outstanding principal	2,570,026	$ 1,860,234
Less current portion		(6,417)
Net carrying value	2,549,224	1,831,011
Borrowing availability under the Revolving Credit Facility	100,000	100,000
The 2017 Senior Credit Facility [Member]
Long-term Debt, Gross	595,026	635,234
Unamortized deferred loan costs	(9,261)	(11,777)
2024 Notes [Member]
Long-term Debt, Gross	525,000
Unsecured Debt, Total	525,000	525,000
Unamortized deferred loan costs	(5,744)	(6,743)
2026 Notes [Member]
Long-term Debt, Gross	700,000
Unsecured Debt, Total	700,000	700,000
Unamortized deferred loan costs	(8,359)	(9,473)
Unamortized premium	4,576	5,187
2027 Notes [Member]
Long-term Debt, Gross	750,000
Unsecured Debt, Total	750,000
Unamortized deferred loan costs	$ (2,014)

Total Long term debt including current portion and before unamortized premium or discount.

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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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