SHARE-BASED COMPENSATION PLANS

We have an incentive plan under which stock options, stock awards, stock units and other share-based compensation may be granted to officers, non-employee directors and key employees of the Company. Under the terms of this plan, 3,250,000 shares were authorized, and 1,461,316 shares are available for grant or issuance as of December 31, 2017. Any issuances under this plan are valued at the fair market value of the common stock on the grant date. The vesting and expiration of any stock option grants and the vesting schedule of any stock awards or stock units are determined by the Compensation and Personnel Committee of our Board of Directors at the time of the grant. Forfeitures are recognized as they occur.

The following table summarizes activity regarding our stock options and awards of shares and stock units since December 31, 2014:



Stock Options					Restricted Stock Units
	Shares		Weighted Average Price			Shares		Weighted Average Price
Balance, December 31, 2014	566,774		$	24.15	Balance, December 31, 2014	634,298		$	34.16
Granted	—		—		Granted	241,274		$	45.23
Expired	(30,000	)	$	12.09	Forfeited	(3,587	)	$	29.56
Exercised	(230,048	)	$	26.71	Vested	(266,497	)	$	32.17
Balance, December 31, 2015	306,726		$	23.42	Balance, December 31, 2015	605,488		$	39.47
Granted	—		—		Granted	191,936		$	46.86
Expired	—		—		Forfeited	(965	)	$	43.13
Exercised	(163,726	)	$	23.73	Vested	(304,171	)	$	35.29
Balance, December 31, 2016	143,000		$	23.06	Balance, December 31, 2016	492,288		$	44.93
Granted	—		—		Granted	198,179		$	68.33
Expired	—		—		Forfeited	(1,200	)	$	60.68
Exercised	(50,000	)	$	20.42	Vested	(180,395	)	$	44.57
Balance, December 31, 2017	93,000		$	24.48	Balance, December 31, 2017	508,872		$	54.13

We recognized $9.9 million, $8.9 million and $8.8 million of compensation expense for stock units awarded to non-employee directors and employees pursuant to incentive plans for the years ended December 31, 2017, 2016 and 2015, respectively. We have $9.3 million of compensation expense, net of income taxes, which will be recognized over the remaining vesting periods of up to approximately five years. In addition, an aggregate of 97,200 restricted stock units granted to employees and non-employee directors vested as of December 31, 2017, but issuance has been deferred up to five years or upon retirement.

All outstanding stock options were fully vested; therefore, no compensation expense was recognized for the years ended December 31, 2017, 2016 and 2015.

As a result of stock option exercises, less than $0.1 million, $0.7 million and $3.8 million of proceeds were received during the years ended December 31, 2017, 2016 and 2015, respectively. The income tax benefit derived in 2017, 2016 and 2015 as a result of such exercises and share-based compensation was $3.9 million, $6.2 million and $1.6 million, respectively, of which $1.6 million, $2.5 million and $1.7 million, respectively, represented excess tax benefits. The total intrinsic value of options (the amounts by which the stock price exceeded the exercise price of the option on the date of exercise) that were exercised during 2017, 2016 and 2015 was $2.3 million, $4.6 million and $4.6 million, respectively.

At December 31, 2017, 2016 and 2015, 93,000 options, 143,000 options and 306,726 options were exercisable, respectively. The weighted average exercise price of exercisable options at December 31, 2017, 2016 and 2015 was approximately $24.48, $23.06 and $23.42, respectively. The total aggregate intrinsic value of options outstanding and exercisable as of December 31, 2017, 2016 and 2015 were approximately $5.3 million, $6.8 million and $7.6 million, respectively.

The following table summarizes information about our outstanding stock options as of December 31, 2017:

We have an employee stock purchase plan. Under the terms of this plan, the maximum number of shares of our common stock that may be purchased is 3,000,000 shares. Generally, our corporate employees and non-union employees of our United States subsidiaries are eligible to participate in this plan. Employees covered by collective bargaining agreements generally are not eligible to participate in this plan.

Stock Options Outstanding and Exercisable

Range of
Exercise Prices

Weighted Average
Remaining Life

Weighted Average
Exercise Price