Note 10 - Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

Notes Tables

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

	Three Months Ended March 31,
	2017					2016
	Shares			Weighted- Average Exercise Price		Shares			Weighted- Average Exercise Price
Beginning balance		216,859		$	8.80		298,740		$	9.97
Issued		-			-		-			-
Exercised		(2,675	)		24.67		(16,759	)		11.80
Forfeited		-			-		(1,100	)		15.48
Expired		-			-		(6,037	)		13.57
Ending balance		214,184		$	8.60		274,844		$	9.76

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

Outstanding:		Stock Options		Weighted-Average		Weighted-Average Remaining
Range of Exercise Prices		Outstanding		Exercise Price		Contractual Life
$5.76	$10.72		154,535	$	5.76		1.56
$10.73	$15.45		47,886		10.83		1.18
$15.46	$20.01		447		16.66		5.97
$20.02	$49.91		11,316		37.59		7.77
			214,184	$	8.60		1.81

Exercisable:		Stock Options		Weighted-Average
Range of Exercise Prices		Exercisable		Exercise Price
$5.76	$10.72		119,837	$	5.76
$10.73	$15.45		47,886		10.83
$15.46	$20.01		447		16.66
$20.02	$49.91		2,906		22.20
			171,076	$	7.49

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

	Three Months Ended		Years Ended December 31,
	March 31, 2017		2016			2015
Expected volatility		n/a		24.23	%		31.21	%
Weighted-Average volatility		n/a		24.23	%		31.21	%
Expected dividends		-		-			-
Expected term (in years)		n/a		7.0			7.0
Risk-free rate		n/a		1.37	%		1.64	%
Weighted-average fair value (grant date)		n/a	$	14.27		$	16.73

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

	Three Months Ended March 31,
	2017					2016
	Shares			Weighted- Average Grant Date Fair Value		Shares			Weighted- Average Grant Date Fair Value
Unvested at beginning		296,192		$	34.61		369,093		$	24.43
Issued		127,620			61.21		139,732			46.17
Forfeited		(327	)		43.07		(766	)		37.48
Vested		(176,134	)		28.73		(195,188	)		22.53
Unvested at end		247,351		$	52.51		312,871		$	35.29