Note 10 - Equity Incentive Plans - Restricted Common Stock and Non-qualified Stock Option Activity (Details) - shares	3 Months Ended						9 Months Ended
	Sep. 30, 2021		Jun. 30, 2021		Mar. 31, 2021		Sep. 30, 2021	Sep. 30, 2020
Total stock options granted (in shares)							4,670,324	0
Restricted Stock [Member]
Number of awards issued/granted (in shares)	3,915,502	[1],[2],[3]	(89,673)	[3],[4]	(121,499)	[5]	3,704,330
Restricted Stock [Member] | Minimum [Member]
Vesting Period (Year)			0 years
Restricted Stock [Member] | Maximum [Member]
Vesting Period (Year)			4 years
Non-qualified Stock Options [Member]
Number of awards issued/granted (in shares)			0		0
Total stock options granted (in shares)	4,668,727	[6],[7]					4,668,727
Restricted Stock and Non-qualified Stock Options [Member] | Minimum [Member]
Vesting Period (Year)	2 years
Restricted Stock and Non-qualified Stock Options [Member] | Maximum [Member]
Vesting Period (Year)	3 years

[1] Includes restricted stock awards granted to employees and directors on August 20, 2021.

[2] Includes shares of common stock cancelled related to the unvested restricted stock awards of certain employees.

[3] Includes shares withheld from employees to cover tax withholding obligations upon the vesting of restricted stock awards.

[4] Includes restricted stock awards granted to employees April 7, 2021, May 3, 2021, and June 7, 2021.

[5] Includes shares of common stock cancelled related to the unvested restricted stock awards of a director and an employee who resigned.

[6] Includes non-qualified stock options cancelled related to the unvested option awards granted to an employee.

[7] Includes non-qualified stock options granted to employees and directors on August 20, 2021.