Note 15 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Year Ended December 31,
	2022		2021		2020
	(Dollars in thousands)
Cost of revenues	$	6,382	$	4,656	$	4,435
Selling and marketing expenses		1,230		766		1,081
General and administrative expenses		4,034		3,746		4,314
Total stock-based compensation expense		11,646		9,168		9,830
Tax effect on stock-based compensation expense		1,270		872		858
Net effect of stock-based compensation expense	$	10,376	$	8,296	$	8,972

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

	Year Ended December 31,
	2022			2021			2020
For stock based awards issued by the Company:
Risk-free interest rates		1.7	%		0.7	%		0.4	%
Expected lives (in weighted average years)		5.3			3.8			5.8
Dividend yield		0.7	%		0.6	%		0.6	%
Expected volatility (weighted average)		34.6	%		36.7	%		28.8	%

	Year Ended December 31,
	2022			2021			2020
Weighted average forfeiture rate		10.2	%		6.1	%		8.2	%

Risk-free interest rates	4.13%	-	4.38%
Expected life (in years)	2	-	3
Dividend yield		0.56%
Expected volatility (weighted average)	43.17%	-	40.57%

Risk-free interest rates	1.31%	-	1.62%
Expected life (in years)	2	-	6
Dividend yield		0.67%
Expected volatility (weighted average)	32.85%	-	46.07%

Risk-free interest rates	0.14%	-	0.16%
Expected life (in years)		1
Dividend yield		0.65%
Expected volatility (weighted average)		43.26%

Risk-free interest rates	0.13%	-	0.51%
Expected life (in years)	2	-	6
Dividend yield		0.61%
Expected volatility (weighted average)	37.68%	-	30.15%

Risk-free interest rates	0.12%	-	0.44%
Expected life (in years)	1	-	6
Dividend yield		0.61%
Expected volatility (weighted average)	45.2%	-	29.4%

Risk-free interest rates		0.44%
Expected life (in years)	2	-	6
Dividend yield		0.63%
Expected volatility (weighted average)		28.14%

Risk-free interest rates	0.44%	-	0.28%
Expected life (in years)	2	-	6
Dividend yield		0.64%
Expected volatility (weighted average)	28.5%	-	35.2%

Risk-free interest rates	0.41%	-	0.17%
Expected life (in years)	2	-	6
Dividend yield		0.64%
Expected volatility (weighted average)	28.5%	-	35.7%

Share-Based Payment Arrangement, Option and Stock Appreciation Rights, Activity [Table Text Block]

	Year Ended December 31,
	2022					2021					2020
	Awards (In thousands)			Weighted Average Exercise Price		Awards (In thousands)			Weighted Average Exercise Price		Awards (In thousands)			Weighted Average Exercise Price
Outstanding at beginning of year		2,025		$	58.70		2,240		$	57.68		1,792		$	50.39
Granted:
SARs (1)		513			71.15		15			77.22		957			68.82
RSUs (2)		109			—		12			—		35			—
PSUs (3)		20			—		—			—		25			—
Exercised		(728	)		52.73		(159	)		40.47		(469	)		45.71
Forfeited		(129	)		62.27		(83	)		64.34		(100	)		55.05
Expired		—			—		—			—		—			—
Outstanding at end of year		1,810			60.08		2,025			58.70		2,240			57.68
Options and SARs exercisable at end of year		749			58.30		881			53.20		704			51.64
Weighted-average fair value of awards granted during the year				$	33.02				$	46.23				$	20.84

Share-Based Payment Arrangement, Option, Exercise Price Range [Table Text Block]

		Awards Outstanding						Awards Exercisable
Exercise Price		Number of Stock-based Awards Outstanding		Weighted Average Remaining Contractual Life in Years		Aggregate Intrinsic Value		Number of Stock-based Awards Exercisable		Weighted Average Remaining Contractual Life in Years		Aggregate Intrinsic Value
$	—		157		2.1	$	13,536		—		—	$	—
	51.71		8		2.0		278		6		2.0		209
	53.16		3		1.9		108		3		1.9		108
	53.44		103		1.5		3,405		103		1.5		3,405
	55.16		295		0.9		9,236		295		0.9		9,236
	57.97		8		1.6		214		8		1.6		214
	63.35		74		0.9		1,719		74		0.9		1,719
	63.40		45		3.5		1,047		23		3.5		524
	67.54		7		3.9		125		7		3.9		125
	68.34		47		3.4		849		23		3.4		424
	69.14		539		3.4		9,357		199		3.4		3,456
	71.15		499		5.2		7,644		—		5.2		—
	71.71		4		2.6		59		3		2.6		44
	76.43		5		2.9		49		5		2.9		49
	76.54		9		4.9		85		—		4.9		—
	78.53		6		4.3		51		—		4.3		—
	90.28		1		4.0		—		—		4		—
			1,810		3.1	$	47,762		749		1.8	$	19,513

		Awards Outstanding						Awards Exercisable
Exercise Price		Number of Stock-based Awards Outstanding		Weighted Average Remaining Contractual Life in Years		Aggregate Intrinsic Value		Number of Stock-based Awards Exercisable		Weighted Average Remaining Contractual Life in Years		Aggregate Intrinsic Value
$	—		66		1.3	$	5,208		—		—	$	—
	42.87		187		0.5		6,796		187		0.5		6,796
	47.46		15		1.9		478		15		1.9		478
	51.71		8		3.0		221		4		3.0		110
	53.16		31		2.9		819		26		2.9		689
	53.44		386		2.5		9,985		227		2.5		5,859
	55.16		296		1.9		7,137		296		1.9		7,137
	57.97		15		2.6		320		15		2.6		320
	58.79		1		0.5		19		1		0.5		19
	63.35		88		1.9		1,401		88		1.9		1,401
	63.40		45		4.5		721		—		4.5		—
	67.54		12		4.9		139		12		4.9		139
	68.34		47		4.4		513		—		4.4		—
	69.14		799		4.4		8,123		1		4.4		12
	71.71		4		3.6		30		2		3.6		15
	72.14		0		0		—		—		0		—
	76.43		8		3.9		24		8		3.9		24
	90.28		1		5		—		—		5		—
			2,025		3.0	$	41,967		882		1.8	$	22,999