Note 8 - Stock-Based Compensation (Details) - Stock Options Outstanding (USD $)	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options Outstanding (in Shares)	496,919	501,334	618,034	722,155
Weighted-Average Exercise Price	$ 11.20	$ 10.34	$ 10.48	$ 10.18
Weighted-Average Remaining Contractual Life	3 years 208 days
Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Exercise Price	$ 5.76
Upper Exercise Price	$ 8.00
Stock Options Outstanding (in Shares)	237,579
Weighted-Average Exercise Price	$ 5.76
Weighted-Average Remaining Contractual Life	4 years 193 days
Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Exercise Price	$ 8.01
Upper Exercise Price	$ 10.00
Stock Options Outstanding (in Shares)	59,344
Weighted-Average Exercise Price	$ 9.79
Weighted-Average Remaining Contractual Life	189 days
Range 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Exercise Price	$ 10.01
Upper Exercise Price	$ 20.00
Stock Options Outstanding (in Shares)	109,994
Weighted-Average Exercise Price	$ 12.55
Weighted-Average Remaining Contractual Life	3 years 105 days
Range 4 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Exercise Price	$ 20.01
Upper Exercise Price	$ 33.44
Stock Options Outstanding (in Shares)	90,002
Weighted-Average Exercise Price	$ 24.81
Weighted-Average Remaining Contractual Life	3 years 131 days