Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

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

Summary of activity for Corporation's stock options

A summary of activity for the Corporation’s stock options as of and for the nine months ended September 30, 2017 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, 2016	407,939		$	32.81	$	6.15	2,453,395		$	21.41
Granted	132,414		53.43		9.94		132,414		53.43
Exercised	—		—		—		(1,341,354	)	16.93
Vested	(161,751	)	37.73		7.07		—		—
Forfeited/expired	(42,885	)	37.68		7.06		(42,885	)	37.68
Outstanding at September 30, 2017	335,717		$	37.95	$	7.09	1,201,570		$	29.36
Exercisable/vested at September 30, 2017							865,853		$	26.03

Assumptions of Black-Scholes option pricing model

The fair value of the stock options granted during the nine months ended September 30, 2017 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions.

Expected dividend yield	3.31		%
Risk-free interest rate	2.05		%
Expected stock price volatility	26.7		%
Expected life of options – in years	6.0
Weighted average fair value of options granted	$	9.94

Summary of activity for restricted stock units and awards

A summary of the activity for restricted stock units as of and for the nine months ended September 30, 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	168,173		51.90
Converted into shares of common stock	(64,750	)	29.30
Forfeited/expired	(8,374	)	47.05
Outstanding at September 30, 2017	393,406		$	41.25

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	(4,165	)	46.23
Nonvested at September 30, 2017	83,905		$	46.23