Note 7 - Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

Notes Tables

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

	Restricted Shares		Weighted Average Grant Date Fair Value
Outstanding at December 31, 2017		463,000	$	17.79
Granted		194,000		25.57
Vested		67,000		17.56
Forfeited or canceled		11,000		18.06
Outstanding at September 30, 2018		579,000	$	25.16

Schedule of Nonvested Performance-based Units Activity [Table Text Block]

	Performance Shares		Weighted Average Grant Date Fair Value
Outstanding at December 31, 2017		669,500	$	17.51
Granted		261,000		25.69
Vested		119,000		17.78
Forfeited or canceled		20,000		18.05
Outstanding at September 30, 2018		791,500	$	20.15