Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

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

Summary of Assumptions for Options Issued

The assumptions for options issued during 2018, 2017, and 2016 are presented below:

	2018		2017		2016
Expected term (in years)	5.3		5.3		5.3
Volatility	23.0	%	24.9	%	29.6	%
Weighted-average risk-free interest rate	2.69	%	1.95	%	1.25	%
Dividend yield	0.74	%	0.60	%	0.80	%

Summary of Options Including Non-Plan Stock Options

A summary of the status of our options as of December 31, 2018, and changes during the year, is presented below:

	2018
	Shares	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Year)	Aggregate Intrinsic Value (In Thousands)
Stock Options:
Outstanding at beginning of year	1,339,106	$	19.08	2.56	$	38,525
Plus: Granted	72,521	48.33
Less: Exercised	613,588	17.63
Forfeited	7,295	47.01
Outstanding at end of year	790,744	22.48		2.18	13,235
Nonvested at end of year	124,348	42.76		5.69	603
Exercisable at end of year	666,396	18.69		1.58	12,923

Schedule of Nonvested Stock Option Outstanding

The following table provides information about our nonvested stock options outstanding at December 31, 2018:

	2018
	Shares	Weighted- Average Exercise Price		Weighted- Average Grant Date Fair Value
Stock Options:
Nonvested at beginning of period	389,134	$	23.25	$	6.24
Plus: Granted	72,521	48.33		11.62
Less: Vested	330,012	20.59		5.69
Forfeited	7,295	47.01		11.38
Nonvested at end of period	124,348	42.76		10.38

Schedule of RSAs and RSUs

The following table summarizes the Company’s RSUs and changes during the year:

	Units (in whole)	Weighted Average Grant-Date Fair Value per Unit
Balance at December 31, 2017	114,388	$	35.54
Plus: Granted	49,561	48.38
Less: Vested	62,500	32.48
Forfeited	5,742	39.77
Balance at December 31, 2018	95,707	43.08