Note 6 - Stockholder's Equity (Details) - Stock Options (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Stock Options [Abstract]
Stock Options Outstanding	1,356,446	3,813,361		4,863,239	5,835,118
Weighted Average Exercise Price (in Dollars per share)	$ 15.86	$ 15.62		$ 15.31	$ 14.61
Weighted-Average Remaining Contractual Term (Years)	1 year 332 days	2 years 204 days		3 years 160 days	4 years 109 days
Aggregate Intrinsic Value (in Dollars)	$ 25,505,753	$ 25,379,573		$ 8,817,049	$ 19,035,591
Options exercisable at December 31, 2013 and expected to vest	1,353,337
Options exercisable at December 31, 2013 and expected to vest (in Dollars per share)	$ 15.86
Options exercisable at December 31, 2013 and expected to vest	1 year 332 days
Options exercisable at December 31, 2013 and expected to vest (in Dollars)	25,437,135
Options exercisable at December 31, 2013	1,274,757
Options exercisable at December 31, 2013 (in Dollars per share)	$ 15.96
Options exercisable at December 31, 2013	1 year 277 days
Options exercisable at December 31, 2013 (in Dollars)	$ 23,843,458
Stock Options Outstanding	171,484	178,484	[1]	152,500
Weighted Average Exercise Price (in Dollars per share)		$ 15.63	[1]	$ 13.96
Stock Options Outstanding	(2,445,523)	(1,151,884)		(685,417)
Weighted Average Exercise Price (in Dollars per share)	$ 15.49	$ 11.62		$ 6.85
Stock Options Outstanding	(11,392)	(76,478)		(438,962)
Weighted Average Exercise Price (in Dollars per share)	$ 15.27	$ 20.90		$ 18.66

[1] Includes 171,484 options granted as a result of the equity award modification discussed above.