Stock-Based Compensation Expense (Tables)

12 Months Ended

Dec. 31, 2022

Effect of Recording Stock-Based Compensation Expense

The effect of recording stock-based compensation ("SBC") expense for continuing operations for the years ended December 31, 2022, 2021 and 2020 is as follows (in thousands):

	Years Ended December 31,
	2022		2021		2020
Research and development	$	1,644	$	1,895	$	2,189
Selling, general and administrative		21,201		23,733		17,954
Total stock-based compensation expense	$	22,845	$	25,628	$	20,143

Employee Stock Purchase Plan

Schedule of Assumptions Used to Value Options Granted

The following assumptions were used to value the ESPP shares:

	Years Ended December 31,
	2022		2021		2020
Expected life (years)		2.0		2.0		2.0
Risk-free interest rate	1.3 - 4.3%		0.1 - 0.2%		0.1 - 1.4%
Dividend yield	1.1 - 2.3%		0.9 - 1.2%		1.4 - 4.0%
Expected volatility	48.5 - 69.0%		52.0 - 52.0%		45.8 - 57.5%

Performance Stock Units

Schedule of Assumptions Used to Value Options Granted

The following assumptions were used to value the performance stock awards subject to market conditions granted in the years ended December 31, 2022, 2021 and 2020:

	Years Ended December 31,
	2022			2021			2020
Expected life (in years)		3.0			3.0			3.0
Risk-free interest rate		2.8	%		0.3	%		0.2	%
Dividend yield		1.2	%		1.0	%		1.4	%
Expected volatility	37.5% - 40.9%				47.9	%		51.3	%