Note 5 - Equity Awards - Option Activity (Details)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Forfeited, canceled (in shares) | shares	160,076
Forfeited, canceled, weighted average exercise price (in dollars per share) | $ / shares	$ 35.92
Nonvested, forfeited, canceled (in shares) | shares
Forfeited, canceled, weighted average grant date fair value (in dollars per share) | $ / shares
Forfeited, canceled (in shares) | shares	(23,971)
Forfeited, canceled, weighted average exercise price (in dollars per share) | $ / shares	$ 12.35
Nonvested, forfeited, canceled (in shares) | shares
Forfeited, canceled, weighted average grant date fair value (in dollars per share) | $ / shares
Forfeited, canceled (in shares) | shares	136,105
Forfeited, canceled, weighted average exercise price (in dollars per share) | $ / shares	$ 40.07
Nonvested, forfeited, canceled (in shares) | shares
Forfeited, canceled, weighted average grant date fair value (in dollars per share) | $ / shares