Note 2 - Stock-Based Compensation (Details) - Stock Options (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Stock Options [Abstract]
Stock Options Outstanding		1,356,446
Weighted Average Exercise Price		$ 15.86
Weighted-Average Remaining Contractual Term (Years)	1 year 255 days	1 year 328 days
Aggregate Intrinsic Value		$ 25,505,753
Options exercisable at March 31, 2014 and expected to vest	1,002,281
Options exercisable at March 31, 2014 and expected to vest	$ 15.88
Options exercisable at March 31, 2014 and expected to vest	1 year 255 days
Options exercisable at March 31, 2014 and expected to vest	22,942,298
Options exercisable at March 31, 2014	942,757
Options exercisable at March 31, 2014	$ 16.01
Options exercisable at March 31, 2014	1 year 6 months
Options exercisable at March 31, 2014	21,459,665
Options exercised	(350,920)
Options exercised	$ 15.83
Options forfeited and expired	(1,167)
Options forfeited and expired	$ 11.48
Stock Options Outstanding	1,004,359
Weighted Average Exercise Price	$ 15.87
Aggregate Intrinsic Value	$ 22,998,787