Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

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, 2018 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, 2017	330,870		$	37.97	$	7.09	1,110,918		$	29.56
Exercised	—		—		—		(295,419	)	23.97
Vested	(78,533	)	37.16		6.94		—		—
Forfeited/expired	(14,926	)	37.51		7.03		(14,928	)	37.51
Outstanding at September 30, 2018	237,411		$	38.27	$	7.14	800,571		$	38.27
Exercisable/vested at September 30, 2018							563,160		$	28.61

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, 2018	83,228		$	46.23
Vested	(41,784	)	46.23
Forfeited	(592	)	46.23
Nonvested at September 30, 2018	40,852		$	46.23

A summary of the activity for RSUs as of and for the nine months ended September 30, 2018 is presented below:

	Number of Units		Weighted-average grant date fair value per unit
Outstanding at December 31, 2017	380,940		$	41.29
Granted	315,072		54.41
Converted into shares of common stock	(70,459	)	28.96
Forfeited/expired	(15,390	)	47.43
Outstanding at September 30, 2018	610,163		$	49.33