Note 9 - Net Income (Loss) Per Share - Antidilutive Securities Excluded From Computation of Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities (in shares)	42	2,178	37	2,511
Employee Stock Option [Member]
Antidilutive Securities (in shares)	42	1,740	31	1,952
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities (in shares)		334	6	395
Performance Shares [Member]
Antidilutive Securities (in shares)		64		81
ESPP [Member]
Antidilutive Securities (in shares)		40		83