The Company is authorized to grant up to 2,650,000 shares of common stock under its 2019 Long-Term Incentive Plan (the “2019 Plan”). The 2019 Plan allows stock-based compensation awards to be granted in a variety of forms, including stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, dividend equivalent rights, bonus stock or other stock-based awards and performance awards. The terms and conditions of the awards granted are established by the Compensation Committee of the Company’s Board of Directors. A total of 303,911 shares were available for future grants under the Plan as of September 30, 2020.

Stock-based compensation expense was as follows for the three and nine months ended September 30, 2020 and 2019 (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Restricted stock units	$	357	$	445	$	1,424	$	3,773
Performance units		535		374		1,226		3,364
Restricted and unrestricted stock		69		242		935		477
Total expense	$	961	$	1,061	$	3,585	$	7,614

Restricted stock unit awards vest subject to the satisfaction of service requirements. The Company recognizes expense related to restricted stock unit awards on a straight-line basis over the requisite service period, which is three years. The grant date fair values of these awards are determined based on the closing price of the Company’s common stock on the date of the grant. As of September 30, 2020, there was $3.1 million of total unrecognized compensation cost related to outstanding restricted stock units. The weighted average period for the units to vest is approximately one year. A summary of employee restricted stock unit awards activity during the nine months ended September 30, 2020 is as follows:

	Number of units			Weighted average grant date fair value		Aggregate intrinsic value (in thousands)
Total awarded and unvested, December 31, 2019		437,559		$	7.83	$	3,474
Granted		351,467			5.86
Vested		(214,804	)		9.14
Forfeited		(3,023	)		6.02
Total awarded and unvested, September 30, 2020		571,199		$	6.14	$	2,508

Performance unit awards issued prior to May 2020 vest subject to the satisfaction of a three-year service requirement and a performance objective which generally is based on the Company’s performance compared to an industry peer group. In May 2020, the Company issued performance unit awards which are scheduled to vest on December 31, 2022 and are subject to a performance objective based on the performance of the Company’s stock over the performance period. All performance unit awards are measured at the grant date fair value using a Monte Carlo valuation method.

As of September 30, 2020, there was $4.1 million of total unrecognized compensation cost related to outstanding performance units. The weighted average period for the units to vest is approximately two years. A summary of performance stock unit awards activity during the nine months ended September 30, 2020 is as follows:

	Number of units			Weighted average grant date fair value		Aggregate intrinsic value (in thousands)
Total awarded and unvested, December 31, 2019		320,120		$	11.26	$	2,522
Granted		618,483			6.21
Vested		(51,858	)		20.89
Forfeited		(55,547	)		16.69
Total awarded and unvested, September 30, 2020		831,198		$	6.54	$	932

The determination of the fair value of the performance unit awards noted above uses significant Level 3 assumptions in the fair value hierarchy including an estimate of the timing of forfeitures, the risk-free interest rate and a volatility estimate tied to the Company’s stock price. The following table presents the assumptions used to determine the fair value for performance stock units granted during the nine months ended September 30, 2020 and 2019:

	Nine Months Ended September 30,
	2020			2019
Volatility		79.70	%		65.10	%
Risk-free interest rate		0.20	%		1.83	%

Effective February 28, 2019, the Company issued an aggregate of 70,409 restricted shares of common stock to two of its officers in connection with retention bonus arrangements entered into between the Company and each of these officers. Twenty-five percent of the restricted shares vested on each of August 28, 2019 and February 28, 2020. In accordance with the terms of the underlying award agreements, the remaining 50% of the restricted shares vested on June 1, 2020.

Pursuant to the Company’s Non-Employee Director Compensation Policy, on June 18, 2019, the Company awarded an aggregate of 53,328 restricted shares of common stock to eight of the non-employee members of its Board of Directors, which shares became fully vested on June 18, 2020. The other non-employee member of the Company’s Board of Directors declined to receive any compensation for his service on the Company’s Board of Directors for 2019.

Pursuant to the Company’s Non-Employee Director Compensation Policy, on August 2, 2019 and October 8, 2019, the Company issued an aggregate of 26,935 and 22,661 unrestricted shares of common stock, respectively, to four of the non-employee members of its Board of Directors who had elected to receive payment of their 2019 annual retainers in shares of the Company’s common stock.

Pursuant to the Company’s Non-Employee Director Compensation Policy, on June 19, 2020, the Company issued an aggregate of 58,335 restricted shares of common stock to five of the non-employee members of its Board of Directors, which shares are scheduled to fully vest on June 19, 2021. The other non-employee member of the Company’s Board of Directors declined to receive any compensation for his service on the Company’s Board of Directors for 2020.

As of September 30, 2020, there was $0.2 million of total unrecognized compensation cost related to restricted and unrestricted stock.