Note 20 - Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Carrying Value and Fair Value by Fair Value Hierarchy of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Marketable securities, fair value		$ 0
Fair Value, Recurring [Member]
Liability-classified restricted stock awards	$ 702
Total recurring	340,438
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Liability-classified restricted stock awards	702
Total recurring	340,438
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Liability-classified restricted stock awards	0
Total recurring	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Liability-classified restricted stock awards	0
Total recurring	0
Corn, Palladium and Finished Goods [Member] | Fair Value, Nonrecurring [Member]
Corn and palladium inventory	566	866
Corn, Palladium and Finished Goods [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Corn and palladium inventory	566	235
Corn, Palladium and Finished Goods [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Corn and palladium inventory	0	631
Corn, Palladium and Finished Goods [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Corn and palladium inventory	0	$ 0
US Treasury Securities [Member] | Fair Value, Recurring [Member]
Marketable securities, fair value	225,792
US Treasury Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable securities, fair value	225,792
US Treasury Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable securities, fair value	0
US Treasury Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable securities, fair value	0
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Recurring [Member]
Marketable securities, fair value	113,944
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable securities, fair value	113,944
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable securities, fair value	0
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable securities, fair value	$ 0