Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2021

Restricted Stock Units (RSUs) [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]

The table below presents the number of RSUs granted, the average grant-date fair value and the number of shares vested for the following periods:

	Nine Months Ended September 30,
	2021	2020
RSUs granted	118,223	281,382
Average grant-date fair value	$13.84	$4.49
Issued upon vesting, net of shares withheld for income taxes	122,911	45,435

Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Payment Arrangement, Performance Shares, Activity

The table below presents the number of PRSUs granted and the number of shares vested for the following periods:

	Nine Months Ended September 30,
	2021	2020
PRSUs granted 1	225,206	145,399
Monte Carlo grant-date fair value 2	$17.74 to $33.31	$2.40 to $16.02
Average grant-date fair value 3	$13.63	not applicable
Issued upon vesting, net of shares withheld for income taxes	7,252	19,402

Schedule of Valuation Assumptions

The ranges for the assumptions used in the Monte Carlo model for these PRSUs granted during 2021, 2020 and 2019 are presented as follows:

	2021 1		2020 1		2019
Expected volatility	131.74% to 134.74%		101.32% to 117.71%		49.9	%
Dividend yield	0.0	%	0.0	%	0.0	%
Risk-free interest rate	0.22% to 0.29%		0.18% to 0.51%		1.66	%
Performance period	2021-2023		2020-2022		2020-2022

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1    One executive officer’s inducement award originally granted in August 2020 was amended in April 2021 to conform vesting conditions to other PRSU awards granted in 2021. The Monte Carlo assumptions for both years are included above.