Equity (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Summary of Option Activity

Stock option activity for the 2010 Stock Plan for the years ended December 31, 2019, 2018 and 2017 is summarized as follows:

	2019				2018				2017
(Shares in thousands)	Number of shares		Weighted average exercise price		Number of shares		Weighted average exercise price		Number of shares		Weighted average exercise price
Options outstanding, beginning of year	1,410		$	18.22	1,869		$	13.46	1,907		$	11.54
Granted	293		33.33		296		31.10		335		21.60
Exercised	(128	)	13.89		(727	)	10.89		(359	)	10.89
Expired or forfeited	—		—		(28	)	26.41		(14	)	12.78
Options outstanding, end of year	1,575		$	21.39	1,410		$	18.22	1,869		$	13.46
Options exercisable, end of year	788		$	15.75	562		$	13.68	872		$	11.11

Summary of Options Outstanding

Options outstanding for the Company’s stock plans at December 31, 2019 are summarized as follows:

(Shares in thousands)	Options outstanding				Options exercisable
Range of exercise prices	Number outstanding	Weighted average remaining life in years	Weighted- average exercise price		Number exercisable	Weighted average exercise price
$9.88 to $11.71	71	1.1 years	$	11.71	71	$	11.71
$12.20 to $12.20	416	3.1 years	12.20		292	12.20
$13.49 to $13.49	226	2.1 years	13.49		226	13.49
$21.60 to $21.60	287	4.1 years	21.60		129	21.60
$31.10 to $31.10	282	5.1 years	31.10		70	31.10
$33.33 to $33.33	293	6.1 years	33.33		—	—
	1,575	4.0 years	$	21.39	788	$	15.75

Weighted Average Assumptions Used In Valuation And Resulting Weighted Average Fair Value Per Option Granted

The fair value of each stock option grant was estimated at the date of grant using a Black-Scholes option pricing model. The following table presents the weighted-average assumptions used in the valuation and the resulting weighted-average fair value per option granted for the years ended December 31, 2019, 2018 and 2017:

Employee stock options:	2019			2018			2017
Volatility	31.6		%	28.7		%	26.9		%
Risk-free interest rate	2.5		%	2.4		%	1.7		%
Dividend yield	0.8		%	1		%	—		%
Expected life (years)	4.1			3.9			4.1
Weighted average fair value per option	$	8.89		$	7.35		$	5.25

Summary of Restricted Stock Activity

Restricted stock units are awards of common stock made under the 2010 Stock Plan that are subject to a risk of forfeiture if the awardee terminates employment with the Company prior to the lapse of the restrictions. The value of such restricted stock units is determined using the market price on the grant date. Compensation expense for restricted stock units is generally recognized using the straight-line single-option method. A summary of the Company’s restricted stock unit activity for the years ended December 31, 2019, 2018 and 2017 is presented in the following table:

	2019				2018				2017
(Shares in thousands)	Number of shares		Weighted average grant date fair value		Number of shares		Weighted average grant date fair value		Number of shares		Weighted average grant date fair value
Unvested, beginning of year	1,519		$	21.24	1,857		$	15.86	2,164		$	12.49
Granted	514		34.05		509		31.40		659		22.14
Vested	(679	)	18.89		(732	)	15.07		(801	)	12.22
Forfeited	(100	)	24.82		(115	)	18.58		(165	)	14.48
Unvested, end of year	1,254		27.48		1,519		21.24		1,857		15.86

Summary of Allocation of Share Based Compensation Expense

The following table summarizes the allocation of share-based compensation expense related to employee stock options, restricted stock awards, performance-based restricted stock awards and grants under the employee stock purchase plan for the years ended December 31, 2019, 2018 and 2017:

(In thousands)	2019		2018		2017
Cost of sales	$	1,180	$	1,009	$	1,031
Engineering, research and development expenses	1,901		1,689		1,457
Selling, general and administrative expenses	16,548		14,414		12,818
Share-based compensation expense	19,629		17,112		15,306
Tax benefit	3,626		3,421		4,978
Share-based compensation expense, net of tax	$	16,003	$	13,691	$	10,328