Note 12 - Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	201 7			201 6			201 5
Expected option life in years (1)		6.0			6.0			6.0
Expected stock price volatility percentage (2)		25	%		25	%		25	%
Risk-free interest rate percentage (3)		2.0	%		1.4	%		1.8	%
Expected dividend yield (4)		0.59	%		0.50	%		0.44	%
Fair value as of the date of grant	$	4.34		$	3.17		$	3.58

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

	Shares			Weighted Average Exercise Price
Outstanding at December 31, 201 6		922,934		$	10.94
Granted		136,501			16.32
Exercised		(124,016	)		8.83
Forfeited		(16,836	)		11.43
Outstanding at December 31, 201 7		918,583		$	12.02
Exercisable at December 31, 2017		505,355		$	10.42

Schedule of Nonvested Share Activity [Table Text Block]

	Shares			Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Life (in Years)
Nonvested at December 31, 201 6		444,476		$	3.46		5.0
Granted		136,501			4.34		6.7
Vested		(151,912	)		3.39		3.4
Forfeited		(15,837	)		3.19		4.3
Nonvested at December 31, 201 7		413,228		$	3.79		5.1

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

	Shares			Weighted Average Grant Date Fair Value
Nonvested at December 31, 201 6		253,028		$	11.66
Granted		154,511			14.48
Vested		(37,648	)(1)		12.86
Forfeited		(47,229	)		8.58
Nonvested at December 31, 201 7		322,662		$	13.32