Note 11 - Property, Plant and Equipment (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Finance Lease, Right-of-Use Asset, before Accumulated Amortization	$ 74,599		$ 74,599		$ 112,334
Finance Lease, Right-of-Use Asset, Accumulated Amortization	25,757		25,757		$ 56,761
Finance Lease, Right-of-Use Asset, Amortization	$ 6,428	$ 5,538	$ 15,047	$ 10,502