As of December 31, 2020, the Company has an Omnibus Incentive Plan under which 1,400,000 shares are reserved for restricted stock and stock options grants for employees, as well as stock grants for directors. The plan was originally approved in 2011 and replaced all prior stock-based plans except for shares and options previously issued under those plans. As of December 31, 2020 and 2019, there were 443,370 shares and 502,839 shares, respectively, of the Company’s Common Stock available for grant under the 2011 Omnibus Incentive Plan. The Company recognizes the cost of stock-based awards in net earnings for all of its stock-based compensation plans on a straight-line basis over the service period of the awards. The following sections describe the three types of grants in more detail.

The Company estimates the fair value of its option awards using the Black-Scholes option-pricing formula, and records compensation expense for stock options ratably over the stock option grant’s vesting period. Stock option compensation expense recognized by the Company for the year ended December 31, 2020 was $0.4 million compared to $0.3 million in 2019 and $2.1 million in 2018.

The following table summarizes the transactions of the Company’s stock option plans for the three-year period ended December 31, 2020:

	Number of shares			Weighted- average exercise price
Options outstanding - December 31, 2017		386,283		$	25.74
Options granted		43,778		$	48.20
Options modified		80,642		$	52.44
Options exercised		(53,161	)	$	21.47
Options canceled		(80,642	)	$	37.04
Options forfeited		—		n/a
Options outstanding - December 31, 2018		376,900		$	28.95
Options granted		34,926		$	59.44
Options exercised		(66,969	)	$	29.29
Options forfeited		(7,525	)	$	38.81
Options outstanding - December 31, 2019		337,332		$	31.82
Options granted		41,807		$	62.76
Options exercised		(55,716	)	$	18.99
Options forfeited		(7,229	)	$	50.19
Options outstanding - December 31, 2020		316,194		$	37.75
Price range $ 18.08 — $ 27.18
(weighted-average contractual life of 2.1 years)		106,390		$	22.53
Price range $ 28.33 — $ 42.50
(weighted-average contractual life of 5 years)		102,484		$	33.30
Price range $ 48.20 — $ 72.30	.
(weighted-average contractual life of 8.2 years)		107,320		$	57.09
Options outstanding - December 31, 2020		316,194
Exercisable options —
December 31, 2018		321,122		$	27.16
December 31, 2019		271,252		$	27.17
December 31, 2020		235,829		$	30.82

The following assumptions were used for valuing options granted in the years ended December 31:

	2020			2019
Per share fair value of options granted during the period	$	17.49		$	18.20
Risk-free interest rate		0.64	%		2.52	%
Dividend yield		1.05	%		0.97	%
Volatility factor		30.0	%		32.4	%
Weighted-average expected life in years		7.0			5.3

The expected life is based on historical exercise behavior and the projected exercise of unexercised stock options. The risk-free interest rate is based on the U.S. Treasury yield curve in effect on the date of grant for the respective expected life of the option. The expected dividend yield is based on the expected annual dividends divided by the grant date market value of the Company’s Common Stock. The expected volatility is based on the historical volatility of the Company’s Common Stock.

The following table summarizes the aggregate intrinsic value related to options exercised, outstanding and exercisable as of and for the years ended December 31:

As of December 31, 2020, the unrecognized compensation cost related to stock options was approximately $1.0 million, which will be recognized over a weighted average period of 3.4 years.

Non-employee directors receive an annual award of $58,000 worth of restricted shares of the Company’s Common Stock under the shareholder-approved 2011 Omnibus Incentive Plan. The Company values stock grants for directors at the closing price of the Company’s stock on the day the grant was awarded. The Company records compensation expense for this plan ratably over the annual service period beginning May 1. Director stock compensation expense recognized by the Company for the years ended December 31, 2020 was $0.4 million compared to $0.3 million in 2019 and $0.5 million in 2018. As of December 31, 2020, the unrecognized compensation cost related to the director stock award that is expected to be recognized over the remaining three months is estimated to be approximately $0.1 million.

The Company periodically issues nonvested shares of the Company's Common Stock to certain eligible employees. The Company values restricted stock on the closing price of the Company's stock on the day the grant was awarded. The Company records compensation expense for this plan ratably over the vesting periods. Restricted stock compensation expense recognized by the Company for the year ended December 31, 2020 was $1.0 million compared to $0.9 million in 2019 and $2.1 million in 2018.

The fair value of nonvested shares is determined based on the market price of the shares on the grant date.

	Shares			Fair value per share
Nonvested at December 31, 2017		111,473		$	35.21
Granted		32,268		$	49.10
Modified		30,488		$	52.47
Vested		(68,289	)	$	40.16
Canceled		(30,488	)	$	38.62
Forfeited		(2,650	)	$	36.83
Nonvested at December 31, 2018		72,802		$	42.58
Granted		16,034		$	59.42
Vested		(19,227	)	$	30.08
Forfeited		(5,129	)	$	41.31
Nonvested at December 31, 2019		64,480		$	48.21
Granted		20,758		$	64.19
Vested		(25,044	)	$	39.87
Forfeited		(2,645	)	$	54.35
Nonvested at December 31, 2020		57,549		$	57.33

As of December 31, 2020, there was $1.8 million of unrecognized compensation cost related to nonvested restricted stock that is expected to be recognized over a weighted average period of 2.1 years.