Note 7 - Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Notes Tables

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Three Months Ended March 31,
	2018			2017
Stock-based compensation expense, gross	$	2,157		$	1,337
Income tax benefit at our statutory rate associated with stock-based compensation		(548	)		(521	)
Stock-based compensation expense, net	$	1,609		$	816

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

	Three Months Ended
	March 31, 2018					March 31, 2017
				Weighted-					Weighted-
				Average					Average
	Number			Grant Date		Number			Grant Date
	of			Fair Value		of			Fair Value
	Shares			Per Share		Shares			Per Share
Restricted common stock:
Outstanding - beginning of period		503,685		$	11.14		396,033		$	12.06
Granted		318,196		$	15.25		307,943		$	10.40
Vested		(225,570	)	$	11.21		(200,291	)	$	11.82
Outstanding - end of period		596,311		$	13.31		503,685		$	11.14
Restricted Class A common stock:
Outstanding - beginning of period		462,632		$	10.63		415,082		$	10.15
Granted (1)		220,080		$	12.65		198,220		$	10.60
Vested		(274,926	)	$	10.48		(227,526	)	$	10.00
Outstanding - end of period		407,786		$	11.82		385,776		$	10.47
Restricted stock units - common stock:
Outstanding - beginning of period		209,500		$	15.70
Granted		-		$	-
Vested		(209,500	)	$	15.70
Forfeited		-		$	-
Outstanding - end of period		-		$	-