Share-Based Compensation (Tables)

3 Months Ended

Mar. 31, 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 three months ended March 31, 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	126,695		53.72		10.05		126,695		53.72
Exercised	—		—		—		(1,210,264	)	15.92
Vested	(81,584	)	32.81		6.15		—		—
Forfeited/expired	(3,940	)	32.81		6.15		(3,940	)	32.81
Outstanding at March 31, 2017	449,110		$	38.71	$	7.25	1,365,886		$	29.24
Exercisable/vested at March 31, 2017							916,776		$	24.60

Assumptions of Black-Scholes option pricing model

The fair value of the stock options granted during the three months ended March 31, 2017 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions.

Expected dividend yield	3.32		%
Risk-free interest rate	2.06		%
Expected stock price volatility	26.9		%
Expected life of options – in years	6.0
Weighted average fair value of options granted	$	10.05

Summary of activity for restricted stock units and awards

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	(61,049	)	46.23
Forfeited	(1,524	)	46.23
Nonvested at March 31, 2017	303,318		$	46.23

A summary of the activity for restricted stock units as of and for the three months ended March 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	159,462		52.11
Converted into shares of common stock	(40,141	)	26.86
Forfeited/expired	(316	)	32.81
Outstanding at March 31, 2017	417,362		$	40.76