Note 2 - Investment Securities (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Investment [Table Text Block]

	December 31,
	201 8		20 1 7
Cash and cash equivalents:
Cash	$	21,969	$	14,058
Cash equivalents:
Money market funds		4,083		126
Total cash and cash equivalents		26,052		14,184
Marketable securities:
U.S. government notes		1,397		11,870
U.S. government agencies		2,677		—
Municipal securities		200		200
Commercial paper		2,433		1,833
Corporate debt securities		2,816		7,825
Total marketable securities		9,523		21,728
Total cash, cash equivalents and marketable securities	$	35,575	$	35,912

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

December 31, 201 8	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Cash and cash equivalents	$	26,052	$	—	$	—		$	26,052
Marketable investments
U.S. government notes		1,397		—		—			1,397
U.S. government agencies		2,677		—		—			2,677
Municipal securities		200		—		—			200
Commercial paper		2,433		—		—			2,433
Corporate debt securities		2,825		—		(9	)		2,816
Total marketable securities		9,532				(9	)		9,523
Total cash, cash equivalents and marketable securities	$	35,584	$		$	(9	)	$	35,575

December 31, 201 7	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Cash and cash equivalents	$	14,184	$	—	$	—		$	14,184
Marketable investments
U.S. government notes		11,885		—		(15	)		11,870
Municipal securities		201		—		(1	)		200
Commercial paper		1,836		—		(3	)		1,833
Corporate debt securities		7,838		2		(15	)		7,825
Total marketable securities		21,760		2		(34	)		21,728
Total cash, cash equivalents and marketable securities	$	35,944	$	2	$	(34	)	$	35,912

Investments Classified by Contractual Maturity Date [Table Text Block]

	Amount
Due in less than one year	$	9,121
Due in 1 to 3 years		402
Total marketable securities	$	9,523

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

December 31, 201 8	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	4,083	$	—	$	—	$	4,083
Short term marketable investments:
Available-for-sale securities		—		9,523		—		9,523
Total assets at fair value	$	4,083	$	9,523	$	—	$	13,606

December 31, 201 7	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	126	$	—	$	—	$	126
Commercial paper		—		—		—		—
Short term marketable investments:
Available-for-sale securities		—		21,728		—		21,728
Total assets at fair value	$	126	$	21,728	$	—	$	21,854