Stock-Based Compensation

3 Months Ended

Mar. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

Stock-Based Compensation

The Corporation grants equity awards to employees, consisting of stock options, restricted stock, RSUs and PSUs under its Amended and Restated Equity and Cash Incentive Compensation Plan ("Employee Equity Plan"). In addition, employees may purchase stock under the Corporation’s Employee Stock Purchase Plan. The fair value of equity awards granted to employees is recognized as compensation expense over the period during which employees are required to provide service in exchange for such awards. Compensation expense for PSUs is also recognized over the period during which employees are required to provide service in exchange for such awards, however, compensation expense may vary based on the expectations for actual performance relative to defined performance measures.

The Corporation also grants equity awards to non-employee members of its board of directors under the 2011 Directors’ Equity Participation Plan ("Directors’ Plan"). Under the Directors’ Plan, the Corporation can grant equity awards to non-employee holding company and subsidiary bank directors in the form of stock options, restricted stock or common stock.

Equity awards issued under the Employee Equity Plan are generally granted annually and become fully vested over or after a three-year vesting period. The vesting period for non-performance-based awards represents the period during which employees are required to provide service in exchange for such awards. Equity awards under the Directors' Plan generally vest immediately upon grant. Certain events, as defined in the Employee Equity Plan and the Directors' Plan, result in the acceleration of the vesting of equity awards.

The following table presents compensation (benefit) expense and the related tax benefits for equity awards recognized in the consolidated statements of income:

	Three months ended March 31
	2017			2016
	(in thousands)
Stock-based compensation expense	$	734		$	1,436
Tax benefit	(744		)	(433		)
Stock-based compensation expense, net of tax benefit	$	(10	)	$	1,003

For the quarter ended March 31, 2017, the tax benefit exceeded the stock-based compensation expense as a result of excess tax benefits related to stock option exercises during the quarter, which were recorded as a reduction to income tax expense as required under ASU 2016-09.

Stock option fair values are estimated through the use of the Black-Scholes valuation methodology as of the date of grant. Stock options carry terms of up to ten years. Fair values for restricted stock, RSUs and a majority of PSUs are based on the trading price of the Corporation’s stock on the date of grant and earn dividends or dividend equivalents during the vesting period, which are forfeitable if the awards do not vest. The fair value of certain PSUs are estimated through the use of the Monte Carlo valuation methodology as of the date of grant.

As of March 31, 2017, the Employee Equity Plan had 11.5 million shares reserved for future grants through 2023, and the Directors’ Plan had approximately 371,000 shares reserved for future grants through 2021.