Note 4 - Equity, Stock Plan and Warrants (Tables)

6 Months Ended

Jun. 30, 2013

Stockholders' Equity Note [Abstract]

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

A summary of the changes in the total stock options outstanding during the six months ended June 30, 2013 follows:

				Weighted
				Average
	Options			Exercise Price
Outstanding at December 31, 2012		2,254,514		$	7.08
Granted		245,000		$	32.06
Forfeited or expired		(1,667	)	$	7.80
Exercised		(381,718	)	$	6.98
Outstanding at June 30, 2013		2,116,129		$	9.99
Vested and exercisable at June 30, 2013		1,388,536		$	7.20

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The fair values of the Company’s options were estimated on the date of grant using the Black-Scholes valuation model with the following weighted-average assumptions:

	Three Months ended June 30,  2013				Three Months ended June 30,  2012			Six Months ended June 30,  2013				Six Months ended June 30,  2012
Expected life (years)	5 years				5 years			5 years				5 years
Interest rate	0.68	to	1.48	%		0.69	%	0.69	to	1.48	%	0.69	to	0.90	%
Dividend yield			—			—				—				—
Volatility	77.91	to	124.49	%		63.63	%	57.26	to	124.49	%			63.63	%
Forfeiture rate			—			—				—				—
Weighted average fair value of options granted	$		22.70		$	3.00		$		19.75		$		2.92

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

Information regarding outstanding warrants as of June 30, 2013 is as follows:

Grant date	Warrants Outstanding	Exercisable	Weighted Exercise Price		Remaining Life (Years)
December 9, 2004	63,641	63,641	$	20.70	1.42
June 10, 2009	15,796	15,796	$	7.50	5.93
August 31, 2009	24,934	24,934	$	7.50	5.93
October 2, 2009	361,433	361,433	$	5.00	6.33
March 15, 2010	8,337	8,337	$	7.50	6.50
April 5, 2010	930	930	$	7.50	6.50
December 15, 2010	41,462	41,462	$	6.00	2.42
Total	516,533	516,533