Stockholders' Equity - Weighted Average Assumptions of Fair Value Options Using Black-Scholes Option-Pricing Model (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Option-Pricing Model Weighted Average Assumptions
Dividend yield (percent)	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate, minimum (percent)	0.72%	0.26%	0.46%	0.26%
Risk-free interest rate, maximum (percent)	1.02%	0.29%	1.02%	0.66%
Expected life (in years)	5 years	5 years	5 years	5 years
Historical volatility, minimum (percent)	53.51%	52.26%	53.51%	46.50%
Historical volatility, maximum (percent)	53.67%	52.43%	54.55%	52.43%