Share-Based Compensation

The Corporation maintains share-based compensation plans under which it periodically grants share-based awards for a fixed number of shares to certain officers of the Corporation. The fair value of share-based awards is recognized as compensation expense over the requisite service or performance period. During the years ended December 31, 2017, 2016 and 2015, share-based compensation expense related to share-based awards totaled $17.3 million, $14.7 million and $3.7 million, respectively. The excess tax benefit realized from shared-based compensation transactions during the years ended December 31, 2017, 2016 and 2015 was $6.1 million, $2.2 million and $0.5 million, respectively.

During the year ended December 31, 2017, the Corporation granted options to purchase 132,414 shares of common stock, 169,252 restricted stock units and 72,537 shares of common stock to certain officers of the Corporation.

On April 26, 2017, the shareholders of the Corporation approved the Stock Incentive Plan of 2017, which provides for 1,750,000 shares of the Corporation's common stock to be made available for future equity-based awards and canceled the amount of shares available for future grant under prior share-based compensation plans. At December 31, 2017, there were 1,681,101 shares of common stock available for future grants under the Stock Incentive Plan of 2017.

Stock Options

The Corporation issues stock options to certain officers from time to time. The exercise price on stock options equals the current market price of the Corporation's common stock on the date of grant and stock options expire ten years from the date of grant. Stock options granted after 2012 vest ratably over a five-year period. Stock options granted prior to 2013 generally vest ratably over a three-year period. Stock options granted prior to 2016 fully vested upon completion of the merger with Talmer. Stock options assumed by the Corporation in the merger with Talmer were fully vested prior to assumption.

The following summarizes information about stock options outstanding and exercisable at December 31, 2017:



	Options outstanding				Options exercisable
Range of exercise prices per share	Number outstanding	Weighted average exercise price per share		Weighted average contractual term (in years)	Number exercisable	Weighted average exercise price per share		Weighted average contractual term (in years)
$11.09 - 12.80	32,691	$	12.37	2.93	32,691	$	12.37	2.93
$13.20 - 16.24	136,604	15.94		4.92	136,604	15.94		4.92
$19.97 - 21.10	49,546	20.36		2.62	49,546	20.36		2.62
$23.78 - 25.14	232,582	24.56		4.33	232,582	24.56		4.33
$29.45 - 32.81	537,893	31.68		7.62	290,534	30.72		7.15
$46.95 - 53.72	121,602	53.40		9.25	38,091	53.72		9.23
$11.09 - 53.72	1,110,918	$	29.56	6.42	780,048	$	25.99	5.56

The intrinsic value of all outstanding in-the-money stock options and exercisable in-the-money stock options was $26.6 million and $21.4 million, respectively, at December 31, 2017. The aggregate intrinsic values of outstanding and exercisable options at December 31, 2017 were calculated based on the closing market price of the Corporation's common stock on December 31, 2017 of $53.47 per share less the exercise price. Options with intrinsic values less than zero, or "out-of-the-money" options, are not included in the aggregate intrinsic value reported. The total intrinsic value of stock options for the years ended December 31, 2016 and 2015 was $80.4 million and $7.6 million, respectively.

A summary of activity for the Corporation's stock options as of and during the years ended December 31, 2017, 2016 and 2015 is presented below:



	Non-vested stock options outstanding						Stock options outstanding
	Number of options		Weighted- average exercise price per share		Weighted- average grant date fair value per share		Number of options		Weighted- average exercise price per share
Outstanding at December 31, 2014	432,199		$	26.75	$	8.30	1,037,311		$	25.90
Granted	244,165		30.18		8.40		244,165		30.18
Acquired	—		—		—		132,883		12.93
Exercised	—		—		—		(310,985	)	25.10
Vested	(150,224	)	25.57		7.80		—		—
Forfeited/expired	(46,385	)	27.99		8.50		(48,635	)	28.18
Outstanding at December 31, 2015	479,755		$	28.75	$	8.49	1,054,739		$	25.38
Granted	441,167		32.81		6.15		441,167		32.81
Acquired	—		—		—		1,466,408		15.08
Exercised	—		—		—		(450,296	)	20.02
Vested	(454,360	)	28.74		8.49		—		—
Forfeited/expired	(58,623	)	31.10		7.17		(58,623	)	31.10
Outstanding at December 31, 2016	407,939		$	32.81	$	6.15	2,453,395		$	21.41
Granted	132,414		53.43		9.94		132,414		53.43
Exercised	—		—		—		(1,427,159	)	17.50
Vested	(161,751	)	37.73		7.07		—		—
Forfeited/expired	(47,732	)	37.55		7.03		(47,732	)	37.55
Outstanding at December 31, 2017	330,870		$	37.97	$	7.09	1,110,918		$	29.56
Exercisable/vested at December 31, 2017							780,048		$	25.99

Total cash received from option exercises during the years ended December 31, 2017, 2016 and 2015 was $3.2 million, $2.7 million and $2.3 million, respectively, resulting in the issuance of 621,355 shares, 229,055 shares and 134,659 shares, respectively.

At December 31, 2017, unrecognized compensation expense related to stock options totaled $1.9 million and is expected to be recognized over a remaining weighted average period of 3.5 years.

The fair value of the stock options granted during the years ended December 31, 2017, 2016 and 2015 were estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions.



	2017		2016		2015
Expected dividend yield	3.31	%	3.30	%	3.50	%
Risk-free interest rate	2.05	%	1.39	%	1.78	%
Expected stock price volatility	26.7	%	27.9	%	39.1	%
Expected life of options — in years	6.0		6.5		7.0
Weighted average fair value of options granted	$9.94		$6.15		$8.40

The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant and the expected life of the options granted. Expected stock volatility was based on historical volatility of the Corporation's common stock over the expected life of the option. The expected life of options represents the period of time that options granted are expected to be outstanding and is based primarily upon historical experience, including option exercise behavior.

Because of the unpredictability of the assumptions required, the Black-Scholes (or any other valuation) model is incapable of accurately predicting the Corporation's common stock price or of placing an accurate present value on options to purchase its stock. In addition, the Black-Scholes model was designed to approximate value for types of options that are very different from those issued by the Corporation. In spite of any theoretical value that may be placed on a stock option grant, no value is possible under options issued by the Corporation without an increase in the market price per share of the Corporation's common stock over the market price per share of the Corporation's common stock at the date of grant.

Restricted Stock Units

The Corporation grants Performance-Based Restricted Stock Units ("PRSUs") and Time-Based Restricted Stock Units ("TRSUs") (collectively referred to as RSUs) to certain officers from time to time. The PRSUs vest based on the Corporation achieving certain performance target levels and the grantee completing the requisite service period. The PRSUs are eligible to vest from 0.5x to 1.5x the number of units originally granted depending on which, if any, of the performance target levels are met. However, if the minimum performance target levels are not achieved, no shares will become vested or be issued for that respective year's PRSUs. The TRSUs vest upon satisfaction of a service condition. Upon achievement of the performance target level and/or satisfaction of a service condition, as applicable, the RSUs are converted into shares of the Corporation's common stock on a one-to-one basis. Compensation expense related to RSUs is recognized over the expected requisite performance or service period, as applicable.

A summary of the activity for RSUs during the year ended December 31, 2017 is presented below:



	Number of units		Weighted-average grant date fair value per unit
Outstanding at December 31, 2016	298,357		$	32.81
Granted	169,252		51.93
Converted into shares of common stock	(75,639	)	30.73
Forfeited/expired	(11,030	)	47.62
Outstanding at December 31, 2017	380,940		$	41.29

At December 31, 2017, unrecognized compensation expense related to RSUs totaled $9.0 million and is expected to be recognized over a remaining weighted average period of 2.7 years.

Restricted Stock Awards

The Corporation assumed restricted stock awards in the merger with Talmer that vest upon completion of future service requirements. The fair value of these awards is equal to the market price of the Corporation's common stock at the date the awards were assumed with the portion of the fair value related to post-combination service. The Corporation recognizes stock-based compensation expense over the vesting period, using the straight-lined method, based upon the number of shares of restricted stock ultimately expected to vest. If an individual that has been awarded restricted stock awards terminates their employment prior to the end of the vesting period, the unvested portion of the stock is forfeited, with certain exceptions.

The following table provides information regarding nonvested restricted stock awards:



Nonvested restricted stock awards	Number of awards		Weighted-average acquisition-date fair value
Nonvested at January 1, 2017	365,891		$	46.23
Vested	(277,821	)	46.23
Forfeited	(4,842	)	46.23
Nonvested at December 31, 2017	83,228		$	46.23

At December 31, 2017, unrecognized compensation expense related to nonvested restricted stock awards totaled $2.2 million and is expected to be recognized over a remaining weighted average period of 1.1 years.