Note 12 - Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

Notes Tables

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Cost of services-compensation	$	1,673	$	1,462	$	4,236	$	3,503
Selling, general and administrative		3,041		2,532		9,972		5,877
Total	$	4,714	$	3,994	$	14,208	$	9,380

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

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Terms		Aggregate Intrinsic Value
Outstanding balance at December 31, 2017		5,554		$	17.35
Granted		1,010			19.58
Exercised		(151	)		15.81
Forfeitures		(26	)		16.43
Expired		(27	)		22.14
Outstanding balance at June 30, 2018		6,360			17.78		5.37		26,785
Expected to vest at June 30, 2018		1,633			17.68		8.00		6,449
Exercisable at June 30, 2018		3,877		$	17.87		3.72		16,929

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

	Six Months Ended June 30,
	2018		2017
Expected dividend yield		0%		0%
Risk-free interest rate		2.68%		1.74%
Expected volatility		42.43%		44.23%
Expected life (years)		6.00		5.00

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

	Number of Units			Weighted Average Grant Date Fair Value per Unit
Outstanding balance at December 31, 2017		1,346		$	17.65
Granted		761			16.72
Vesting of restricted stock units, net of units withheld for taxes		(364	)		16.93
Units withheld for taxes		(161	)		16.93
Forfeitures		(26	)		16.89
Outstanding balance at June 30, 2018		1,556		$	19.98