Note 2 - Investment Securities (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure Text Block Supplement [Abstract]

Investment [Table Text Block]

	December 31,
	2014		2013
Cash and cash equivalents:
Cash	$	7,761	$	3,816
Cash equivalents:
Money market funds		242		9,926
Commercial paper		1,800		2,500
Total cash and cash equivalents		9,803		16,242
Marketable securities:
U.S. government notes		18,361		10,522
U.S. government agencies		19,800		25,858
Municipal securities		3,607		2,039
Commercial paper		10,695		10,242
Corporate debt securities		18,880		18,170
Total marketable securities		71,343		66,831
Total cash, cash equivalents and marketable securities	$	81,146	$	83,073

Unrealized Gain (Loss) on Investments [Table Text Block]

December 31, 2014	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Cash and cash equivalents	$	9,803	$	—	$	—		$	9,803
Marketable investments
U.S. government notes		18,345		17		(1	)		18,361
U.S. government agencies		19,768		33		(1	)		19,800
Municipal securities		3,607		3		(3	)		3,607
Commercial paper		10,693		2		—			10,695
Corporate debt securities		18,875		13		(8	)		18,880
Total marketable securities		71,288		68		(13	)		71,343
Total cash, cash equivalents and marketable securities	$	81,091	$	68	$	(13	)	$	81,146

December 31, 2013	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Cash and cash equivalents	$	16,242	$	—	$	—		$	16,242
Marketable investments
U.S. government notes		10,516		11		(5	)		10,522
U.S. government agencies		25,823		38		(3	)		25,858
Municipal securities		2,043		1		(5	)		2,039
Commercial paper		10,239		3		—			10,242
Corporate debt securities		18,109		61		—			18,170
Total marketable securities		66,730		114		(13	)		66,831
Total cash, cash equivalents and marketable securities	$	82,972	$	114	$	(13	)	$	83,073

Investments Classified by Contractual Maturity Date [Table Text Block]

	Amount
Due in less than one year (fiscal year 2015)	$	37,023
Due in 1 to 3 years (fiscal year 2016 - 2017)		34,320
	$	71,343

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

December 31, 2014	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	242	$	—	$	—	$	242
Commercial paper		—		1,800		—		1,800
Short term marketable investments:
Available-for-sale securities		—		71,343		—		71,343
Total assets at fair value	$	242	$	73,143	$	—	$	73,385

December 31, 2013	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	9,926	$	—	$	—	$	9,926
Commercial paper		—		2,500		—		2,500
Short term marketable investments:
Available-for-sale securities		—		66,831		—		66,831
Total assets at fair value	$	9,926	$	69,331	$	—	$	79,257

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	Amount
Balance at December 31, 2011	$	3,027
Total gains or losses (realized or unrealized)
Included in other comprehensive income (loss)		262
Settlements		(3,289	)
Balance at December 31, 2012, 2013 and 2014	$	—