Note 10 - Stockholders' Equity (Deficit) - Activity Under the Equity Incentive Plans (Details) shares in Thousands	3 Months Ended
	Dec. 31, 2018 $ / shares shares
Outstanding, beginning balance (in shares) | shares	4,407
Outstanding, weighted average exercise price, beginning balance (in dollars per share) | $ / shares	$ 2.64
Exercised/Released (in shares) | shares
Exercised/Released, weighted average exercise price (in dollars per share) | $ / shares
Cancelled (in shares) | shares	(306)
Cancelled, weighted average exercise price (in dollars per share) | $ / shares	$ 2.25
Outstanding, ending balance (in shares) | shares	4,101
Outstanding, , weighted average exercise price, ending balance (in dollars per share) | $ / shares	$ 2.61
Vested and expected to vest (in shares) | shares	4,024
Vested and expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 2.62
Restricted Stock Units (RSUs) [Member]
Outstanding, beginning balance (in shares) | shares	315
Outstanding, weighted average exercise price, beginning balance (in dollars per share) | $ / shares	$ 1.87
Exercised/Released (in shares) | shares	(192)
Exercised/Released, weighted average exercise price (in dollars per share) | $ / shares	$ 1.88
Cancelled (in shares) | shares
Cancelled, weighted average exercise price (in dollars per share) | $ / shares
Outstanding, ending balance (in shares) | shares	123
Outstanding, weighted average exercise price, ending balance (in dollars per share) | $ / shares	$ 1.85