Note 6 - Stockholders' Equity and Equity Compensation (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended				12 Months Ended			3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended
	Feb. 28, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Through the Open Market Repurchase Program [Member]	Jun. 30, 2014 In Connection with Equity Compensation Programs [Member]	Dec. 31, 2014 In Connection with Equity Compensation Programs [Member]	Jun. 30, 2014 Stock Awards [Member]	Dec. 31, 2013 Stock Awards [Member]	Jun. 30, 2014 Deferred Stock Units [Member]	Jun. 30, 2013 Deferred Stock Units [Member]	Jun. 30, 2014 Deferred Stock Units [Member]	Jun. 30, 2013 Deferred Stock Units [Member]	Dec. 31, 2013 Deferred Stock Units [Member]	Jun. 30, 2014 Employee Stock Option [Member]	Jun. 30, 2013 Employee Stock Option [Member]	Jun. 30, 2014 Employee Stock Option [Member]	Jun. 30, 2013 Employee Stock Option [Member]	Jun. 30, 2014 2013 Employee Plan [Member]	Jun. 30, 2014 2013 Employee Plan [Member] Stock Awards [Member]	Jun. 30, 2014 2011 Director Plan [Member]	Jun. 30, 2014 Deferred Compensation, Share-based Payments [Member] 2011 Director Plan [Member]
Note 6 - Stockholders' Equity and Equity Compensation (Details) [Line Items]
Stock Repurchase Program, Authorized Amount	$ 20,000,000							$ 10,000,000
Stock Repurchased During Period, Shares (in Shares)						591,923	290,917
Stock Repurchased During Period, Value						13,800,000	6,800,000
Treasury Stock Acquired, Average Cost Per Share (in Dollars per share)						$ 23.36	$ 23.49
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)																				2,895,000		250,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number									720,732	555,025	216,765		216,765		214,455						1,968,999		135,396
Allocated Share-based Compensation Expense		1,000,000	900,000	1,900,000	2,100,000						0	0	788,000	890,000		100,000	400,000	500,000	1,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		$ 12,800,000		$ 12,800,000												$ 400,000		$ 400,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition				2 years 3 months 11 days														1 year 0 months 7 days
Price Per Share For Intrinsic Value Calculation Stock Options (in Dollars per share)		$ 23.27	$ 22.51	$ 23.27	$ 22.51