Note 6 - Leases - Lease Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating lease cost	$ 4,912	$ 5,501	$ 15,050	$ 16,891
Short-term lease cost	5,422	8,125	16,288	20,846
Total lease cost	$ 10,334	$ 13,626	$ 31,338	$ 37,737