Stock Plans

Under various stock plans, officers, employees, and outside directors have received or may receive grants of restricted stock, stock units, stock appreciation rights or options to purchase common stock. Grants have been made at the discretion of the Committees of the Board of Directors. Grants generally vest either on a straight-line basis over four years or on a cliff basis over three years. Shares offered under the plan are authorized but unissued shares or treasury shares.

Recipients of restricted stock do not pay any cash consideration to the Company for the shares, have the right to vote all shares subject to such grant, and there were no grants outstanding that received dividends prior to vesting. Restricted stock grants made on or after July 28, 2009, contain forfeitable rights to dividends. Dividends for these grants are accrued on the dividend payment dates but are not paid until the shares vest, and dividends accrued for shares that ultimately do not vest are forfeited. Recipients of stock units do not pay any cash consideration for the units, do not have the right to vote, and do not receive dividends with respect to such units.

The Company recognizes compensation expense equal to the grant-date fair value for all stock-based payment awards that are expected to vest. This expense is recorded on a straight-line basis over the requisite service period of the entire award, unless the awards are subject to performance conditions, in which case the Company recognizes compensation expense over the requisite service period of each separate vesting tranche. The Company determines the grant-date fair value of its restricted stock and stock unit awards using the fair market value on the grant date, unless the awards are subject to market conditions, in which case the Company utilizes a binomial-lattice model (i.e., Monte Carlo simulation model). The Monte Carlo simulation model utilizes multiple input variables to determine the stock-based compensation expense.

During the year ended December 31, 2018, the Company granted performance shares to its executives in the form of restricted stock. The shares granted contain (1) a performance condition based on earnings per share, and (2) a performance condition based on Return on Invested Capital (“ROIC”). The ROIC performance condition measures the Company’s performance against a peer group. Shares will be delivered at the end of the three year vesting and ROIC performance period based on the Company’s actual performance compared to the peer group. Actual shares earned will range from seventy-five percent (75%) to one hundred twenty-five percent (125%) of the target award after any adjustment made for the EPS performance condition.

Stock-based compensation expense consisted of the following (in thousands):



	Years Ended December 31,
	2018		2017		2016
Restricted stock and stock units - expense	$	44,953	$	42,191	$	42,699

Unrecognized compensation cost is expected to be recognized over the next four years. Total unrecognized compensation cost, net of estimated forfeitures, consisted of the following (in thousands):



	December 31,
	2018		2017		2016
Restricted stock and stock units - unrecognized future costs	$	65,557	$	62,730	$	60,481

The following table reflects activity under all stock plans from December 31, 2015 through December 31, 2018, and the weighted average exercise prices (in thousands, except per share amounts):



	Restricted Stock Plans without Market-Condition				Restricted Stock Plans with Market-Condition				Stock Option Plans
	Number of Shares/ Units			Weighted Average Grant Date Fair Value	Number of Shares/ Units			Weighted Average Grant Date Fair Value	Number of Shares/ Units			Weighted Average Exercise Price Per Share
Outstanding, December 31, 2015		1,052		$46.88		992		$52.89		12		$32.36
Granted		772		$38.47		358		$45.93		—		—
Exercised		—		—		—		—		(7	)	$32.36
Restrictions lapsed		(545	)	$42.42		(364	)	$43.04		—		—
Forfeited		(36	)	$41.28		(36	)	$43.04		(5	)	$32.36
Outstanding, December 31, 2016		1,243		$43.78		950		$54.42		—		—
Granted		904		$47.86		50		$50.09		—		—
Restrictions lapsed		(616	)	$44.09		(384	)	$50.09		—		—
Forfeited		(41	)	$43.68		—		—		—		—
Outstanding, December 31, 2017		1,490		$46.13		616		$56.76		—		—
Granted		811		$57.04		—		—		—		—
Restrictions lapsed		(568	)	$47.62		(129	)	$71.86		—		—
Forfeited		(40	)	$49.10		(129	)	$71.86		—		—
Outstanding, December 31, 2018		1,693		$50.78		358		$45.93		—		—

The total pre-tax intrinsic value of stock options exercised and the total fair value of shares vested during the years ended December 31, 2018, 2017 and 2016, are reflected in the following table (in thousands):



	Years Ended December 31,
	2018		2017		2016
Total pre-tax intrinsic value of stock options exercised	$	—	$	—	$	52
Total fair value of shares vested	$	40,583	$	50,385	$	39,302

At December 31, 2018, the total number of available shares to grant under the plans (consisting of either restricted stock, stock units, stock appreciation rights or options to purchase common stock) was approximately 3.2 million.