Note 7 - Long-term Leases - Maturity of Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
2020, finance leases	$ 7,998
2020, operating leases	35,733
2021, finance leases	5,200
2021, operating leases	35,443
2022, finance leases	5,200
2022, operating leases	35,112
2023, finance leases	5,200
2023, operating leases	34,688
2024, finance leases	4,767
2024, operating leases	34,403
Thereafter, finance leases
Thereafter, operating leases	99,877
Total minimum lease payments, finance leases	28,365
Total minimum lease payments, operating leases	275,256
Less: amounts representing interest, finance leases	(3,475)
Less: amounts representing interest, operating leases	(55,122)
Present value of future minimum lease payments, finance leases	24,890
Present value of future minimum lease payments, operating leases	220,134
Less: current portion, finance leases	(6,780)	$ (3,924)
Less: current portion, operating leases	(23,353)
Noncurrent lease liabilities, finance leases	18,110	19,128
Noncurrent lease liabilities, operating leases	$ 196,781