Note 2 - Stock-Based Compensation (Details) - Stock Options (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Stock Options [Abstract]
Outstanding at January 1, 2014		1,356,446
Outstanding at January 1, 2014		$ 15.86
Outstanding at January 1, 2014	1 year 219 days	1 year 328 days
Outstanding at January 1, 2014		$ 25,505,753
Options exercised	(555,147)
Options exercised	$ 16.29
Options forfeited and expired	(7,641)
Options forfeited and expired	$ 10.78
Outstanding at June 30, 2014	793,658
Outstanding at June 30, 2014	$ 15.60
Outstanding at June 30, 2014	1 year 219 days	1 year 328 days
Outstanding at June 30, 2014	21,230,524
Options exercisable at June 30, 2014 and expected to vest	792,359
Options exercisable at June 30, 2014 and expected to vest	$ 15.61
Options exercisable at June 30, 2014 and expected to vest	1 year 219 days
Options exercisable at June 30, 2014 and expected to vest	21,188,533
Options exercisable at June 30, 2014	749,481
Options exercisable at June 30, 2014	$ 15.74
Options exercisable at June 30, 2014	1 year 146 days
Options exercisable at June 30, 2014	$ 19,943,748