Note 2 - Stock-based Compensation - Stock Incentive Plan Activities (Details) - Incentive Plan [Member] shares in Thousands	3 Months Ended
	Mar. 31, 2017 $ / shares shares
Awards Available (in shares)	2,273
Options Outstanding (in shares)	12,095
Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 6.55
Stock option awards granted (in shares)	(2,296)
Stock option awards granted (in shares)	2,296
Stock option awards granted (in dollars per share) | $ / shares	$ 5.51
Stock option awards exercised (in shares)	(319)
Stock option awards exercised (in dollars per share) | $ / shares	$ 3.50
Stock option awards cancelled (in shares)	617
Stock option awards cancelled (in shares)	(617)
Stock option awards cancelled (in dollars per share) | $ / shares	$ 10.90
Awards Available (in shares)	591
Options Outstanding (in shares)	13,455
Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 6.24
Restricted Stock Units (RSUs) [Member]
Restricted stock unit awards granted (in shares)	(5)
Restricted stock unit awards cancelled (in shares)	2