Note 13 - Fair Value Measurements - Schedule of Carrying Value and Fair Value by Fair Value Hierarchy of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Recurring [Member]
Liability-classified restricted stock awards	$ (904)
Total	385,300
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Liability-classified restricted stock awards	(904)
Total	385,335
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Liability-classified restricted stock awards	0
Total	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Liability-classified restricted stock awards	0
Total	(35)
Fair Value, Recurring [Member] \| Warrant [Member]
Derivative warrant liability	(35)	$ (31)
Derivative liability, fair value	35	31
Fair Value, Recurring [Member] \| Warrant [Member] \| Fair Value, Inputs, Level 1 [Member]
Derivative warrant liability	0	0
Derivative liability, fair value	(0)	0
Fair Value, Recurring [Member] \| Warrant [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative warrant liability	0	0
Derivative liability, fair value	(0)	0
Fair Value, Recurring [Member] \| Warrant [Member] \| Fair Value, Inputs, Level 3 [Member]
Derivative warrant liability	(35)	(31)
Derivative liability, fair value	35	31
Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Marketable securities, fair value	266,892
Fair Value, Recurring [Member] \| US Treasury Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Marketable securities, fair value	266,892
Fair Value, Recurring [Member] \| US Treasury Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Marketable securities, fair value	0
Fair Value, Recurring [Member] \| US Treasury Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Marketable securities, fair value	0
Fair Value, Recurring [Member] \| US Government-sponsored Enterprises Debt Securities [Member]
Marketable securities, fair value	119,347
Fair Value, Recurring [Member] \| US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Marketable securities, fair value	119,347
Fair Value, Recurring [Member] \| US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Marketable securities, fair value	0
Fair Value, Recurring [Member] \| US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Marketable securities, fair value	0
Fair Value, Nonrecurring [Member] \| Corn, Palladium and Finished Goods [Member]
Corn and palladium	504	866
Fair Value, Nonrecurring [Member] \| Corn, Palladium and Finished Goods [Member] \| Fair Value, Inputs, Level 1 [Member]
Corn and palladium	504	235
Fair Value, Nonrecurring [Member] \| Corn, Palladium and Finished Goods [Member] \| Fair Value, Inputs, Level 2 [Member]
Corn and palladium	0	631
Fair Value, Nonrecurring [Member] \| Corn, Palladium and Finished Goods [Member] \| Fair Value, Inputs, Level 3 [Member]
Corn and palladium	$ 0	$ 0

Fair Value, Recurring [Member]