Equity Incentive Awards (Tables)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Summary of Restricted Stock Activities and Related Information

A summary of our restricted stock activities and related information, as adjusted for stock split, is as follows:

	Number of Shares	Weighted Average Grant Date Fair Value Per Share
Balance at December 31, 2018	299,702	$42.78
Shares granted	193,262	$55.51
Shares vested	(74,222)	$43.72
Balance at December 31, 2019	418,742	$48.32
Shares granted	151,104	$56.07
Shares vested	(221,055)	$47.74
Balance at December 31, 2020	348,791	$53.06
Shares granted	162,955	$50.42
Shares vested	(196,839)	$60.91
Balance at December 31, 2021	314,907	$53.98

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

The fair value of stock options granted was estimated on the grant date using the Black-Scholes-Merton model. The following table includes the assumptions made in the valuation, as adjusted for stock split:

	2021	2020
Dividend Yield	2.1%	2.1%
Risk-free interest rate	1.0%	0.3%
Expected Life	5.6 years	5.6 years
Expected Volatility	26.1%	49.2%
Weighted Average Grant Date Fair Value Per Share	$18.04	$29.58

Summary of Stock Option Activity

A summary of our stock option activity and related information, as adjusted for stock split, is as follows:

	Shares Subject To Options	Weighted Average Exercise Price Per Share	Weighted Average Outstanding Contractual Life (in years)	Average Intrinsic Value (in millions)
Balance at December 31, 2018	47,100	$36.95	7.3	$0.5
Options exercised	(5,600)	$9.43		$0.2
Balance at December 31, 2019	41,500	$40.65	7.3	$1.2
Options issued	16,090	$66.81
Balance at December 31, 2020	57,590	$47.96	7.2	$0.9
Options issued	16,185	$68.74
Balance at December 31, 2021	73,775	$52.52	6.9	$2.6
Exercisable at December 31, 2021	57,450	$48.08	6.3	$2.3