Note 8 - Stock-Based Compensation (Details) - Stock Options Exercisable (USD $)	6 Months Ended
	Jun. 30, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options Exercisable (in Shares)	394,931
Weighted-Average Exercise Price	$ 10.74
Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Price Range	$ 5.76
Upper Price Range	$ 8.00
Stock Options Exercisable (in Shares)	180,669
Weighted-Average Exercise Price	$ 5.76
Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Price Range	$ 8.01
Upper Price Range	$ 10.00
Stock Options Exercisable (in Shares)	59,344
Weighted-Average Exercise Price	$ 9.79
Range 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Price Range	$ 10.01
Upper Price Range	$ 20.00
Stock Options Exercisable (in Shares)	88,556
Weighted-Average Exercise Price	$ 12.73
Range 4 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Price Range	$ 20.01
Upper Price Range	$ 33.44
Stock Options Exercisable (in Shares)	66,362
Weighted-Average Exercise Price	$ 22.48