Note 5 - Stock-Based Compensation (Details) (USD $)	1 Months Ended		3 Months Ended			6 Months Ended		12 Months Ended
	Apr. 30, 2013	Mar. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Note 5 - Stock-Based Compensation (Details) [Line Items]
Maximum Period Of Common Stock Granted			10			10
Annual Increments To Be Vested In Common Stock Units			20.00%			20.00%
Stock or Unit Option Plan Expense			$ 0		$ 194,000
Allocated Share-based Compensation Expense						129,000	387,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in Shares)			0	0			39,784
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options							647,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value							34,000
(in Shares)	6,729	14,416						125,133	147,661
GrantSharesAveragePriceDuringPeriodRestrictedStockUnitAward (in Dollars per share)	$ 18.91	$ 20.57						$ 18.24	$ 14.78
Restricted Stock Units (RSUs) [Member]
Note 5 - Stock-Based Compensation (Details) [Line Items]
Stock or Unit Option Plan Expense			492,000		409,000
Allocated Share-based Compensation Expense						1,100,000	762,000
(in Shares)						21,145
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized			$ 2,000,000			$ 2,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition						1 year 109 days
2005 Incentive Plan [Member]
Note 5 - Stock-Based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)			2,654,098			2,654,098
Restricted Stock Units Granted in 2011, 2012 and 2013 [Member]
Note 5 - Stock-Based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period						2 years