Note 10 - Property, Plant and Equipment (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Finance Lease, Right-of-Use Asset, before Accumulated Amortization	$ 81,571		$ 81,571		$ 52,729
Finance Lease, Right-of-Use Asset, Accumulated Amortization	43,375		43,375		$ 31,373
Finance Lease, Right-of-Use Asset, Amortization	$ 5,538	$ 3,920	$ 10,502	$ 7,834