Note 7 - Income Taxes - Changes in Valuation Allowances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Balance at the beginning of the period	$ 512,711	$ 443,398	$ 507,159
Additions attributable to the Merger	187,319	0	0
Additions not attributable to the Merger	160,299	72,025	312
Reductions	(31,242)	(2,712)	(64,073)
Balance at end of period	$ 829,087	$ 512,711	$ 443,398