Note 5 - Stockholders' Equity (Details) - Repurchase of Equity Securities (USD $)	1 Months Ended
	Jun. 30, 2013	May 31, 2013	Apr. 30, 2013	Mar. 31, 2013	Feb. 28, 2013	Jan. 31, 2013
Repurchase of Equity Securities [Abstract]
Total Number of Common Shares Repurchased				20,000	102,473	215,746
Average Price Paid Per Common Share (in Dollars per share)				$ 35.27	$ 37.73	$ 34.65
Total Number of Common Shares Purchased as Part of Publicly Announced Plans or Programs				373,619	353,619	251,146
Maximum Number (or Approximate Dollar Value) of Common Shares that May Yet Be Purchased Under the Plans or Programs	86,745	86,745	86,745	86,745	87,450	91,319