Note 2 - Stock-Based Compensation (Details) - Plan Option Plan Status (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Plan Option Plan Status [Abstract]
Stock Options Outstanding		3,813,361
Weighted Average Exercise Price of Stock Options Outstanding (in Dollars per share)		$ 15.62
Weighted Average Remaining Contractual Term of Stock Options Outstanding	2 years 51 days	2 years 204 days
Aggregate Intrinsic Value of Stock Options Outstanding (in Dollars)		$ 25,379,573
Options exercisable at June 30, 2013 and expected to become exercisable	2,690,171
Options exercisable at June 30, 2013 and expected to become exercisable (in Dollars per share)	$ 16.04
Options exercisable at June 30, 2013 and expected to become exercisable (in Dollars)	21,741,742
Options exercisable at June 30, 2013 and expected to become exercisable	2 years 47 days
Options vested and exercisable at June 30, 2013	2,564,933
Options vested and exercisable at June 30, 2013 (in Dollars per share)	$ 16.08
Options vested and exercisable at June 30, 2013 (in Dollars)	20,644,282
Options vested and exercisable at June 30, 2013	2 years 3 days
Options exercised	(1,110,102)
Options exercised (in Dollars per share)	$ 14.58
Options forfeited and expired	(6,881)
Options forfeited and expired (in Dollars per share)	$ 19.31
Stock Options Outstanding	2,696,378
Weighted Average Exercise Price of Stock Options Outstanding (in Dollars per share)	$ 16.04
Weighted Average Remaining Contractual Term of Stock Options Outstanding	2 years 51 days	2 years 204 days
Aggregate Intrinsic Value of Stock Options Outstanding (in Dollars)	$ 21,804,890