Note 6 - Long-term Leases - Maturity of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
2020, finance leases	$ 5,200
2020, operating leases	35,569
2021, finance leases	5,200
2021, operating leases	35,236
2022, finance leases	5,200
2022, operating leases	34,869
2023, finance leases	5,200
2023, operating leases	34,475
2024, finance leases	867
2024, operating leases	34,319
Thereafter, finance leases	0
Thereafter, operating leases	74,150
Total minimum lease payments, finance leases	21,667
Total minimum lease payments, operating leases	248,618
Less: amounts representing interest, finance leases	(2,538)
Less: amounts representing interest, operating leases	(45,709)
Present value of future minimum lease payments, finance leases	19,129
Present value of future minimum lease payments, operating leases	202,909
Less: current portion, finance leases	(4,166)	$ (3,924)
Less: current portion, operating leases	(24,243)	0
Noncurrent lease liabilities, finance leases	14,963	19,128
Noncurrent lease liabilities, operating leases	$ 178,666	$ 0