Note 16 - Reportable Segments (Details Textual) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Number of Material Formations		150
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	21.00%	21.00%
Revenue, Cumulative Adjustments	[1]		$ 105

[1] Amount represents the negative impact of a cumulative adjustment to reduce revenue in the amount of $105 million recorded during the first quarter of 2020. The adjustment was associated with a previously recorded commercial benefit asset, reflected as a prepayment, to a customer with a long-term supply agreement that exited its production of LCD panels.