Note 5 - Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2016

Notes Tables

Class of Treasury Stock [Table Text Block]

	Repurchases Occurring in the Six Months Ended June 30, 2016				Cumulative Repurchases as of June 30, 2016
	Shares		Average Price		Shares		Average Price
2011 Share Repurchase Authorization		599,123	$	79.21		2,327,636	$	51.09
2016 Share Repurchase Authorization		622,225	$	78.52		622,225	$	78.52

Dividends Declared [Table Text Block]

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Dividend amount per share	$	0.25	$	0.20	$	0.45	$	0.36
Total amount of dividend (in thousands)		6,373		5,266		11,524		9,482