Note 3 - Long-term Debt - Long-term Debt Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2016		Dec. 31, 2015
2014 Senior Credit Facility	$ 1,781,438
Total outstanding principal	1,781,438		$ 1,231,438
Net carrying value	1,756,747		1,220,084
2014 Senior Credit Facility [Member]
2014 Senior Credit Facility	556,438	[1]	556,438
Unamortized deferred loan costs	(12,158)		(6,136)
Borrowing availability under the Revolving Credit Facility	60,000		50,000
2020 Notes [Member]
Unsecured Debt			675,000
Unamortized deferred loan costs			(9,317)
Unamortized premium			4,099
2024 Notes [Member]
2014 Senior Credit Facility	525,000
Unsecured Debt	525,000
Unamortized deferred loan costs	(7,742)
2026 Notes [Member]
2014 Senior Credit Facility	700,000
Unsecured Debt	700,000
Unamortized deferred loan costs	(10,588)
Unamortized premium	$ 5,797

[1] Pursuant to the 2017 Senior Credit Facility, the maturity date of the term loan was extended to February 7, 2024.