Stock-Based Compensation

The Company's 2004 Fourth Amended and Restated Stock Option and Incentive Plan (the "Plan”) provides for awarding 20,150,000 (adjusted for stock splits) shares of common stock plus (i) shares covered by forfeited, expired, and canceled options granted under prior plans; and (ii) shares tendered as full or partial payment for the purchase price of an award or to satisfy tax withholding obligations. At December 31, 2017, a total of 3,536,418 shares were available for issuance. The Plan provides for the granting of nonqualified and incentive stock options having maximum ten-year terms to purchase common stock at its market value on the award date; stock appreciation rights based on common stock fair market values with settlement in common stock or cash; restricted stock awards; restricted stock units; and performance awards with settlement in common stock or cash on achievement of specific business objectives. Options become exercisable in various percentages over periods ranging up to five years.

The cost of employee services received in exchange for awards of equity instruments is referred to as share-based payments and is based on the grant date fair-value of those awards. Stock-based compensation includes compensation expense, recognized over the applicable vesting periods, for share-based awards. The Company uses the Black-Scholes-Merton option pricing model to determine the fair value of stock options granted to employees. Stock-based compensation totaled $33.6 million, $41.3 million, and $61.1 million for the years ended December 31, 2017, 2016, and 2015, respectively.

The income tax benefit related to stock-based compensation expense was $19.0 million, $18.0 million, and $28.5 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Stock options

Expense related to stock options issued to eligible employees under the Plan is recognized over their vesting period on a straight- line basis. Stock options generally vest over five years and have contractual terms of ten years. All options outstanding at December 31, 2017 and December 31, 2016 were exercisable.



	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Terms (Years)	Aggregate Intrinsic Value
						(in millions)
Options outstanding at December 31, 2016	60,793		$	8.12	1.9	$1.2
Granted	—		—
Exercised	(26,450	)	8.12
Cancelled	—		—
Options outstanding at December 31, 2017	34,343		$	8.12	0.9	$1.0

At December 31, 2017, there was no unrecognized compensation expense related to stock options. The intrinsic value of options exercised totaled $0.5 million, zero, and $0.7 million during the years ended December 31, 2017, 2016, and 2015, respectively.

Restricted stock

Restricted share awards consist of restricted stock, restricted stock units, and performance units. Restricted stock and restricted stock units generally vest for periods ranging from one to fifteen years from the date of grant. Certain restricted stock and restricted stock units vest in their entirety upon the employee's retirement from the Company, taking into consideration the employee's age and years of service to the Company, as defined more specifically in the Company's benefit plans. Restricted stock and restricted stock units granted to non-employee directors under the Plan generally vest one year from the grant date and are released at that time or upon completion of the directors' service to the Company. Expense related to restricted stock and restricted stock units issued to eligible employees under the Plan is recognized ratably over the vesting period or to the date on which retirement eligibility is achieved, if shorter. Performance units are granted to employees based upon a target level; however, depending upon the achievement of certain specified goals during the performance period, performance units may be adjusted to a level ranging between 0% and 200% of the target level. The performance units vest upon certification by the Human Resources Committee of the Board of Directors of the achievement of the specified performance goals. Expense related to performance units is recognized ratably from their award date to the end of the performance period, generally three years. Forfeitures are recognized as reduction to expense in the period in which they occur.



	Number of Restricted Share Awards		Weighted Average Grant-Date Fair Value per Award
Restricted share awards outstanding at December 31, 2016	6,749,083		$	22.35
Granted	2,060,027		28.87
Vested	(1,840,119	)	31.09
Forfeited	(158,610	)	24.27
Restricted share awards outstanding at December 31, 2017	6,810,381		$	21.91

At December 31, 2017, unrecognized compensation expense related to restricted share awards totaled $70.2 million which will be recognized over a weighted average period of 4.2 years. The total vesting-date fair value of shares vested and released during the years ended December 31, 2017, 2016, and 2015 was $50.2 million, $47.0 million, and $76.9 million, respectively. The weighted average grant-date fair value of restricted share awards granted during the years ended December 31, 2017, 2016, and 2015 was $28.87, $19.06, and $24.31 per share, respectively.