Note 3 - Investments (Tables)

12 Months Ended

Dec. 31, 2014

Investments Schedule [Abstract]

Available-for-sale Securities [Table Text Block]

	December 31, 2014
	Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Available-for-sale securities:
US treasury securities	$	2,056	$	1	$	—		$	2,057
Municipal bonds		19,686		43		(17	)		19,712
Corporate notes/bonds		16,381		32		(21	)		16,392
Asset backed securities		750		—		(3	)		747
Total investments	$	38,873	$	76	$	(41	)	$	38,908

	December 31, 2013
	Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Available-for-sale securities:
US treasury securities	$	25,061	$	11	$	—		$	25,072
Municipal bonds		34,912		105		(34	)		34,983
Corporate notes/bonds		28,565		105		(22	)		28,648
Certificate of deposit		1,500		1		—			1,501
Asset backed securities		685		1		—			686
Total investments	$	90,723	$	223	$	(56	)	$	90,890

Investments Classified by Contractual Maturity Date [Table Text Block]

	Cost		Fair Value
Due in one year or less	$	13,613	$	13,656
Due between one and five years		25,260		25,252
	$	38,873	$	38,908