Stock-Based Compensation

Stock-based compensation expense for each employee and director is presented in the same statement of operations caption as their cash compensation. Stock-based compensation expense by statement of operations caption and the related income tax benefit were as follows:



	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2018		2017		2018		2017
Cost of sales	$	21	$	19	$	61	$	53
Research and development expenses	200		149		556		412
Selling, general and administrative expenses:
Employees	1,671		1,843		4,936		5,562
Outside directors	247		1,910		1,255		3,449
Total employee and director stock-based compensation expense	$	2,139	$	3,921	$	6,808	$	9,476

Income tax benefit	$	441	$	603	$	1,423	$	2,307

Stock Options

Stock option activity was as follows:



	Number of Options (in 000's)		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in 000's)
Outstanding at December 31, 2017	520		$	42.56
Granted	119		44.95
Exercised	(35	)	24.67			$	744
Forfeited/canceled/expired	(7	)	27.74
Outstanding at September 30, 2018 ⁽¹⁾	597		$	44.27	4.34	$	2,972
Vested and expected to vest at September 30, 2018⁽¹⁾	597		$	44.27	4.34	$	2,972
Exercisable at September 30, 2018 ⁽¹⁾	414		$	41.74	3.64	$	2,972

⁽¹⁾

The aggregate intrinsic value represents the total pre-tax value (the difference between our closing stock price on the last trading day of the third quarter of 2018 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had they all exercised their options on September 30, 2018. This amount will change based on the fair market value of our stock.

The assumptions we utilized in the Black-Scholes option pricing model and the resulting weighted average fair value of stock option grants were the following:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Weighted average fair value of grants	$	—		$	—		$	14.26		$	19.61
Risk-free interest rate	—		%	—		%	2.51		%	1.75		%
Expected volatility	—		%	—		%	33.09		%	34.25		%
Expected life in years	0.00			0.00			4.53			4.52

As of September 30, 2018, we expect to recognize $2.3 million of total unrecognized pre-tax stock-based compensation expense related to non-vested stock options over a remaining weighted-average life of 1.9 years.

Restricted Stock

Non-vested restricted stock award activity was as follows:



	Shares (in 000's)		Weighted-Average Grant Date Fair Value
Non-vested at December 31, 2017	162		$	61.19
Granted	167		42.65
Vested	(75	)	60.02
Forfeited	(11	)	55.94
Non-vested at September 30, 2018	243		$	49.03

As of September 30, 2018, we expect to recognize $8.8 million of total unrecognized pre-tax stock-based compensation expense related to non-vested restricted stock awards over a weighted-average life of 1.8 years.