Share-Based Compensation (Tables)

6 Months Ended

Jun. 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 six months ended June 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	—		—		—		(279,808	)	23.64
Vested	(77,388	)	37.01		6.93		—		—
Forfeited/expired	(13,190	)	38.12		7.14		(13,190	)	38.12
Outstanding at June 30, 2018	240,292		$	38.27	$	7.14	817,920		$	31.45
Exercisable/vested at June 30, 2018							577,628		$	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	(253	)	46.23
Nonvested at June 30, 2018	41,191		$	46.23

A summary of the activity for RSUs as of and for the six months ended June 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	295,995		54.43
Converted into shares of common stock	(63,154	)	28.20
Forfeited/expired	(10,520	)	48.09
Outstanding at June 30, 2018	603,261		$	48.99