Share-Based Compensation and Other Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2020

Restricted Stock Units (RSUs)

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

Activity of Awarded Restricted Stock Units

The following table summarizes activity for our most recent fiscal year with respect to awarded RSUs:

	Restricted Stock Units	Weighted-Average Grant Date Fair Value
Balance at beginning of year	136,876	$	49.76
Granted	281,382	$	4.49
Vested	(63,916)	$	43.30
Forfeited	(35,062)	$	27.83
Balance at end of year	319,280	$	13.56

Performance Restricted Stock Units [Domain]

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

Schedule of Share-based Payment Award, Equity Instruments Other than Options, Valuation Assumptions

The ranges for the assumptions used in the Monte Carlo model for the PRSUs granted during 2020, 2019 and 2017 are presented as follows:

	2020	2019
Expected volatility	101.32% to 117.71%	49.9	%
Dividend yield	0.0%	0.0%
Risk-free interest rate	0.18% to 0.51%	1.66	%

Activity of Awarded Performance-based RSUs

The following table summarizes activity for our most recent fiscal year with respect to PRSUs:

	Performance Restricted Stock Units	Weighted-Average Grant Date Fair Value
Balance at beginning of year	79,914	$	52.73
Granted	145,399	$	7.79
Vested	(31,146)	$	58.35
Forfeited	(20,635)	$	55.99
Balance at end of year	173,532	$	13.68

As of December 31, 2020, we had $1.5 million of unrecognized compensation cost attributable to PRSUs. We expect that cost to be recognized over a weighted-average period of 1.3 years.