Note 6 - Stockholder's Equity (Details) - Summary of Outstanding and Exercisable Options (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	1,356,446	3,813,361	4,863,239	5,835,118
Outstanding, Weighted Average Remaining Contractual Life	1 year 277 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 15.86	$ 15.62	$ 15.31	$ 14.61
Number of Options Exerciseable	1,274,757
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 15.96
One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	159,981
Outstanding, Weighted Average Remaining Contractual Life	2 years 51 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 10.46
Number of Options Exerciseable	140,945
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 10.36
One [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	0.76
One [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	12.42
Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	193,422
Outstanding, Weighted Average Remaining Contractual Life	2 years 73 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 14.36
Number of Options Exerciseable	159,617
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 14.50
Two [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	12.57
Two [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	14.89
Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	11,494
Outstanding, Weighted Average Remaining Contractual Life	1 year 116 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 14.93
Number of Options Exerciseable	10,882
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 14.93
Three [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	14.93
Three [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	14.96
Four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	485,881
Outstanding, Weighted Average Remaining Contractual Life	1 year 299 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 15.03
Number of Options Exerciseable	485,881
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 15.03
Four [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	15.03
Four [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	15.03
Five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	223,686
Outstanding, Weighted Average Remaining Contractual Life	1 year 83 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 16.97
Number of Options Exerciseable	205,322
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 17.07
Five [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	15.13
Five [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	17.92
Six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	137,282
Outstanding, Weighted Average Remaining Contractual Life	2 years 251 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 19.29
Number of Options Exerciseable	130,726
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 19.31
Six [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	18.17
Six [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	19.53
Seven [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	131,109
Outstanding, Weighted Average Remaining Contractual Life	1 year 302 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 21.55
Number of Options Exerciseable	127,793
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 21.56
Seven [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	19.56
Seven [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	23.02
Eight [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	12,564
Outstanding, Weighted Average Remaining Contractual Life	2 years 339 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 23.09
Number of Options Exerciseable	12,564
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 23.09
Eight [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	23.09
Eight [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	23.09
Nine [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	22
Outstanding, Weighted Average Remaining Contractual Life	2 years 262 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 23.50
Number of Options Exerciseable	22
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 23.50
Nine [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	23.50
Nine [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	23.50
Ten [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	1,005
Outstanding, Weighted Average Remaining Contractual Life	1 year 167 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 24.67
Number of Options Exerciseable	1,005
Exercisable, Weighted Average Exercise Price (in Dollars per share)	$ 24.67
Ten [Member] | Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	24.67
Ten [Member] | Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	24.67