Note 8 - Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

Notes Tables

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

	Shares			Weighted-Average Grant-Date Fair Value
Non-vested at December 31, 2017		497,322		$	22.46
Granted		280,590			28.19
Vested		(239,599	)		23.64
Forfeited		(7,110	)		25.27
Non-vested at June 30, 2018		531,203		$	24.91
Vested but unissued at June 30, 2018		234,799		$	25.14

Phantom Share Units (PSUs) [Member]

Notes Tables

Share-based Compensation, Activity [Table Text Block]

Phantom Stock Plan	Shares			Fair Value
Outstanding at December 31, 2017		89,180		$	27.50
Granted		8,946			27.75
Forfeited		-			-
Distributions		(32	)		27.18
Outstanding at June 30, 2018		98,094		$	26.10
Vested at June 30, 2018		97,515		$	26.10