Note 6 - Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2014

Note 6 - Stock-Based Compensation (Tables) [Line Items]

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

	Three Months Ended March 31,
	2014					2013
	Shares			Weighted-Average Exercise Price		Shares			Weighted-Average Exercise Price
Beginning Balance		501,334		$	10.34		722,155		$	10.18
Issued		21,000			32.77		3,300			20.03
Exercised		(19,027	)		13.13		(52,480	)		8.91
Forfeited		(110	)		5.76		(330	)		5.76
Expired		(408	)		9.37		(15,640	)		10.79
Ending Balance		502,789		$	11.18		657,005		$	10.32

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

						Weighted-Average
Outstanding:		Stock Options		Weighted-Average		Remaining
Range of Exercise Prices		Outstanding		Exercise Price		Contractual Life
$5.76	$8.00		237,969	$	5.76		4.78
$8.01	$10.00		64,450		9.72		0.73
$10.01	$20.00		109,994		12.55		3.54
$20.01	$33.44		90,376		24.79		3.60
			502,789	$	11.18		3.78

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

	Three Months Ended			Years Ended December 31,
	March 31, 2014			2013			2012
Expected Volatility		34.25	%		34.12	%		36.64	%
Weighted-Average Volatility		34.24	%		34.12	%		36.64	%
Expected Dividends		0.0	%		0.0	%		0.0	%
Expected Term (In years)		7.5			7.5			7.5
Risk-Free Rate		2.11	%		1.31	%		1.13	%
Weighted-Average Fair Value (Grant date)	$	13.49		$	7.83		$	6.35

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

	Three Months Ended March 31,
	2014					2013
	Shares			Weighted-Average Grant Date Fair Value		Shares			Weighted-Average Grant Date Fair Value
Unvested at Beginning		614,580		$	18.71		348,353		$	13.79
Issued		78,947			33.24		421,425			20.63
Forfeited		(434	)		15.67		-			-
Vested		(181,967	)		17.59		(154,705	)		13.06
Unvested at End		511,126		$	21.36		615,073		$	18.66

Exercisable Stock Options [Member]

Note 6 - Stock-Based Compensation (Tables) [Line Items]

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

Exercisable:			Stock Options		Weighted-Average
Range of Exercise Prices			Exercisable		Exercise Price
$5.76	0	$8.00		181,059	$	5.76
$8.01		$10.00		64,450		9.72
$10.01		$20.00		88,116		12.74
$20.01		$33.44		66,736		22.47
				400,361	$	10.72