Note 1 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Summary of Valuation Allowance [Table Text Block]

Years ended December 31:	Beginning balance January 1,		Additional provisions to (reversal of) allowance			Write-offs and other deductions			Ending balance December 31,
201 7	$	1,345	$	454		$	(343	)	$	1,456
201 6	$	1,857	$	(241	)	$	(271	)	$	1,345
201 5	$	1,767	$	1,100		$	(1,010	)	$	1,857

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

(in thousands except per share data)
	201 7		2016		2015
Numerator:
Net income	$	55,439	$	16,835	$	42,085
Denominator:
Denominator for basic income per share – weighted-average shares		18,279		18,182		18,145
Effect of dilutive securities:
Equivalent shares issuable upon conversion of unvested restricted shares		93		84		161
Equivalent shares issuable upon conversion of unvested employee stock options		-		-		5
Denominator for diluted income per share adjusted weighted-average shares and assumed conversions		18,372		18,266		18,311
Net income per share:
Basic income per share	$	3.03	$	0.93	$	2.32
Diluted income per share	$	3.02	$	0.92	$	2.30