13. Share‑Based Compensation

The Company’s 1998 Stock Incentive Plan, as amended and restated (the “SI Plan”) allows us to grant equity compensation awards, including nonvested stock, as part of our overall compensation program to attract and retain key personnel and encourage a greater personal financial investment in the Company, thereby promoting the long-term growth of the Company. A maximum of 35.6 million shares of common stock are authorized for issuance under the SI Plan and as of December 31, 2018, 2,121,728 shares of common stock were available for issuance under the SI Plan. In addition, we may make incentive payments under the Company Executive Incentive Plan, as amended and restated (the “EIP”) in the form of cash, nonvested stock or a combination thereof. Incentive awards paid under the EIP in the form of nonvested stock are issued out of shares reserved for issuance under the SI Plan. Generally, shares of common stock subject to an award that expires or is cancelled, forfeited, exchanged, settled in cash or is terminated will again be available for awards under the SI Plan.

Nonvested stock awards are valued on the date of grant and have no purchase price. These awards have historically vested over four years in 33 1/3% increments on the second, third and fourth anniversaries of the grant date; however, awards granted on or after December 31, 2016 vest in 25% increments on the first anniversary of the grant date. The Company has issued nonvested stock awards to non-employee directors. These awards generally have the same terms as awards issued to employees, except awards granted on or after January 2, 2017 fully vest on the first anniversary of the grant date and changes in the Company’s share price result in variable compensation expense over the vesting period.

Beginning in 2017, the Company established a Cash Settled RSU Plan (the “RSU Plan”), which allows the Company to grant cash-settled restricted stock units (“RSU”) to attract and retain key personnel and enable them to participate in the long-term growth of the Company. Unvested RSUs have no purchase price and vest in 25% increments over four years, beginning on the first anniversary of the grant date. On the vesting date, RSU holders receive a lump sum cash payment equal to the fair market value of one share of the Company’s common stock, par value $0.01, for each RSU that has vested, subject to applicable tax withholdings. We treat RSUs as liability-classified awards and, therefore, account for them at fair value based on the closing price of our common stock on the reporting date, which results in variable compensation expense over the vesting period.

Nonvested shares and nonvested RSU’s are forfeited upon the termination of employment with or service to the Company, as applicable, or service on the Board of Directors, dependent upon the circumstances of termination. Except for restrictions placed on the transferability of nonvested shares, holders of nonvested shares have full stockholders’ rights during the term of restriction, including voting rights and the rights to receive cash dividends. Since nonvested RSUs are not shares of Company stock, holders of nonvested RSUs are not entitled to voting rights, but are entitled to dividend equivalent payments for each RSU equal to the dividend paid on one share of our common stock.

A summary of nonvested share activity and related fair value for the year ended December 31, 2018 follows:


		Weighted
		Average
	Nonvested	Grant Date
	Stock Shares	Fair Value
Nonvested at December 31, 2017	5,088,640	$	27.26
Granted	1,561,155		20.87
Vested	(2,061,297)		32.02
Forfeited	(494,738)		24.23
Nonvested at December 31, 2018	4,093,760	$	22.79

A summary of nonvested RSU activity for the year ended December 31, 2018 follows:


		Nonvested
		Cash-Settled Units
Nonvested at December 31, 2017		1,213,029
Granted		1,105,087
Vested		(343,711)
Forfeited		(212,345)
Nonvested at December 31, 2018		1,762,060

For the years ended December 31, 2018, 2017 and 2016 compensation expense related to nonvested shares totaled $51.6 million, $57.7 million and $51.5 million, respectively.

The deferred income tax benefit from the compensation expense related to nonvested stock was $10.0 million, $12.2 million and $19.2 million for the years ended December 31, 2018, 2017 and 2016, respectively. These benefits will be recognized upon vesting and may increase or decrease depending on the fair value of the shares on the date of vesting. As of December 31, 2018, the remaining unamortized expense of $60.6 million is expected to be recognized over a weighted average period of 2.2 years.

The total fair value of shares vested (at vest date) during the years ended December 31, 2018, 2017 and 2016, was $41.0 million, $20.8 million and $26.7 million, respectively. The Company withholds a portion of each employee’s vested shares to satisfy income tax withholding obligations of the Company with respect to vesting of the shares.