Note 6 - Stock-Based Compensation (Details) - Stock Options Outstanding (USD $)	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options Outstanding (in Shares)	617,671	722,155	847,414	919,371
Weighted-Average Exercise Price	$ 10.48	$ 10.18	$ 10.03	$ 10.23
Weighted-Average Remaining Contractual Life	3 years 204 days
Exercise Price Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price - Minimum	$ 5.76
Exercise Price - Maximum	$ 8.00
Stock Options Outstanding (in Shares)	251,775
Weighted-Average Exercise Price	$ 5.80
Weighted-Average Remaining Contractual Life	5 years 146 days
Exercise Price Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price - Minimum	$ 8.01
Exercise Price - Maximum	$ 10.00
Stock Options Outstanding (in Shares)	159,638
Weighted-Average Exercise Price	$ 9.19
Weighted-Average Remaining Contractual Life	332 days
Exercise Price Range 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price - Minimum	$ 10.01
Exercise Price - Maximum	$ 20.00
Stock Options Outstanding (in Shares)	110,292
Weighted-Average Exercise Price	$ 12.55
Weighted-Average Remaining Contractual Life	4 years 102 days
Exercise Price Range 4 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price - Minimum	$ 20.01
Exercise Price - Maximum	$ 24.46
Stock Options Outstanding (in Shares)	95,966
Weighted-Average Exercise Price	$ 22.54
Weighted-Average Remaining Contractual Life	2 years 105 days