Our 2015 Omnibus Incentive Plan allows for the granting of stock, restricted stock, restricted stock units, stock options, performance shares and performance share units. We had 561,073 shares available to grant at December 31, 2020.

Compensation expense is determined using the grant date fair value estimated in accordance with the provisions of accounting standards for stock compensation and is recognized over the vesting periods of the individual awards. As of December 31, 2020, total unrecognized compensation expense related to non-vested stock awards was approximately $12 million and is expected to be recognized over a weighted-average period of 2 years. Stock-based compensation expense, which is included in Operations and maintenance on the accompanying Consolidated Statements of Income, was as follows for the years ended December 31 (in thousands):

The Company has not issued any stock options since 2014 and has 5,000 stock options outstanding at December 31, 2020. The amount of stock options granted and related exercise activity are not material to the Company’s consolidated financial statements.

The fair value of restricted stock and restricted stock unit awards equals the market price of our stock on the date of grant.

The shares carry a restriction on the ability to sell the shares until the shares vest. The shares substantially vest over three years, contingent on continued employment. Compensation expense related to the awards is recognized over the vesting period.


	Restricted Stock	Weighted-Average Grant Date Fair Value
	(in thousands)
Balance at January 1, 2020	192	$	65.66
Granted	116	69.49
Vested	(90)	63.30
Forfeited	(22)	65.30
Balance at December 31, 2020	196	$	69.05

The weighted-average grant-date fair value of restricted stock granted and the total fair value of shares vested during the years ended December 31, were as follows:


	Weighted-Average Grant Date Fair Value		Total Fair Value of Shares Vested
			(in thousands)
2020	$	69.49	$	6,722
2019	$	73.66	$	8,438
2018	$	57.31	$	6,776

As of December 31, 2020, there was $10.3 million of unrecognized compensation expense related to non-vested restricted stock that is expected to be recognized over a weighted-average period of 2.2 years.

Certain officers of the Company and its subsidiaries are participants in a performance share award plan, a market-based plan. Performance shares are awarded based on our total shareholder return over designated performance periods as measured against a selected peer group. In addition, certain stock price performance must be achieved for a payout to occur. The final value of the performance shares will vary according to the number of shares of common stock that are ultimately granted based upon the actual level of attainment of the performance criteria.

The performance awards are paid 50% in cash and 50% in common stock. The cash portion accrued is classified as a liability and the stock portion is classified as equity. In the event of a change-in-control, performance awards are paid 100% in cash. If it is determined that a change-in-control is probable, the equity portion of $2.7 million at December 31, 2020 would be reclassified as a liability.


			Possible Payout Range of Target
Grant Date	Performance Period	Target Grant of Shares	Minimum	Maximum
January 1, 2020	January 1, 2020 - December 31, 2022	36	0%	200%
January 1, 2019	January 1, 2019 - December 31, 2021	36	0%	200%
January 1, 2018	January 1, 2018 - December 31, 2020	49	0%	200%


	Equity Portion			Liability Portion
		Weighted-Average Grant Date Fair Value (a)			Weighted-Average Fair Value at
	Shares			Shares	December 31, 2020
	(in thousands)			(in thousands)
Performance Shares balance at beginning of period	67	$	64.32	67
Granted	19	81.42		19
Forfeited	(2)	73.89		(2)
Vested	(23)	63.52		(23)
Performance Shares balance at end of period	61	$	69.71	61	$	52.42

(a) The grant date fair values for the performance shares granted in 2020, 2019 and 2018 were determined by Monte Carlo simulation using a blended volatility of 18%, 21% and 21%, respectively, comprised of 50% historical volatility and 50% implied volatility and the average risk-free interest rate of the three-year United States Treasury security rate in effect as of the grant date.


Performance Period	Year Paid	Stock Issued	Cash Paid		Total Intrinsic Value
January 1, 2017 to December 31, 2019	2020	14	$	1,100	$	2,199
January 1, 2016 to December 31, 2018	2019	44	$	2,860	$	5,720
January 1, 2015 to December 31, 2017	2018	—	—		—

On January 27, 2021, the Compensation Committee of our Board of Directors determined that the Company’s total shareholder return for the January 1, 2018 through December 31, 2020 performance period was at the 55th percentile of its peer group and confirmed a payout equal to 112.35% of target shares, valued at $3.3 million. The payout was fully accrued at December 31, 2020.

As of December 31, 2020, there was $2.0 million of unrecognized compensation expense related to outstanding performance share plans that is expected to be recognized over a weighted-average period of 1.7 years.