Note 11 - Property, Plant and Equipment (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Finance Lease, Right-of-Use Asset, before Accumulated Amortization	$ 76,021		$ 76,021		$ 112,334
Finance Lease, Right-of-Use Asset, Accumulated Amortization	29,403		29,403		$ 56,761
Finance Lease, Right-of-Use Asset, Amortization	$ 6,409	$ 6,178	$ 21,456	$ 16,680