Stock-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2016

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

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

The following table presents compensation expense and related tax benefits for all equity awards recognized in the consolidated statements of income:

	2016			2015			2014
	(in thousands)
Compensation expense	$	6,556		$	5,938		$	5,865
Tax benefit	(2,679		)	(2,011		)	(1,608		)
Stock-based compensation, net of tax	$	3,877		$	3,927		$	4,257

Schedule of Unrecognized Compensation Cost, Nonvested Awards

The following table presents compensation expense and related tax benefits for restricted stock awards, RSUs and PSUs recognized in the consolidated statements of income, and included as a component of total stock-based compensation in the preceding table:

	2016			2015			2014
	(in thousands)
Compensation expense	$	6,165		$	4,646		$	4,345
Tax benefit	(2,158		)	(1,626		)	(1,510		)
Restricted stock compensation, net of tax	$	4,007		$	3,020		$	2,835

Schedule of Share-based Compensation, Stock Options, Activity

The following table provides information about stock option activity for the year ended December 31, 2016:

	Stock Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value (in millions)
Outstanding as of December 31, 2015	2,980,087		$	12.31
Exercised	(920,924	)	11.70
Forfeited	(263,685	)	14.33
Expired	(465,295	)	16.19
Outstanding as of December 31, 2016	1,330,183		$	10.98	4.7 years	$	10.4
Exercisable as of December 31, 2016	1,247,736		$	10.87	4.5 years	$	9.9

Schedule of Nonvested Share Activity

The following table provides information about nonvested stock options, restricted stock, RSUs and PSUs granted under the Employee Equity Plan and Directors' Plan for the year ended December 31, 2016:

	Nonvested Stock Options				Restricted Stock/RSUs/PSUs
	Options		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2015	349,852		$	2.82	1,388,389		$	12.16
Granted	—		—		447,130		13.86
Vested	(247,727	)	2.71		(292,583	)	11.73
Forfeited	(19,678	)	2.84		(17,221	)	12.20
Nonvested as of December 31, 2016	82,447		$	3.14	1,525,715		$	12.74

Schedule Of Options Exercised

The following table presents information about stock options exercised:

	2016		2015		2014
	(dollars in thousands)
Number of options exercised	920,924		490,151		215,047
Total intrinsic value of options exercised	$	4,619	$	1,442	$	568
Cash received from options exercised	$	10,240	$	4,936	$	2,068
Tax deduction realized from options exercised	$	4,328	$	1,389	$	530

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The fair value of stock option awards under the Employee Equity Plan was estimated on the grant date using the Black-Scholes valuation methodology, which is dependent upon certain assumptions, as summarized in the table below. No options were granted in 2016 and 2015 under the Employee Equity Plan.

	2014
Risk-free interest rate	2.44	%
Volatility of Corporation’s stock	28.05	%
Expected dividend yield	2.36	%
Expected life of options	7 Years

The fair value of certain PSUs with market-based performance conditions granted in 2016 under the Employee Equity Plan was estimated on the grant date using the Monte Carlo valuation methodology performed by a third-party valuation expert. This valuation is dependent upon certain assumptions, as summarized in the following table:

	2016		2015		2014
Risk-free interest rate	0.92	%	0.86	%	0.91	%
Volatility of Corporation’s stock	20.75	%	20.08	%	29.63	%
Expected life of PSUs	3 Years		3 Years		3 Years

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The following table summarizes activity under the ESPP:

	2016		2015		2014
ESPP shares purchased	109,665		121,890		132,640
Average purchase price per share (85% of market value)	$	12.37	$	10.86	$	10.31
Compensation expense recognized (in thousands)	$	240	$	234	$	241