XML 63 R65.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Stock-based Compensation - Schedule of Key Assumptions Utilized in Fair Value Calculation (Details) - Outstanding stock options
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (years) 6 years 6 years 6 years
Expected stock price volatility (in percentage) 74.00% 78.00% 84.00%
Risk-free interest rate (in percentage) 1.90% 2.70% 2.00%
Dividend yield (in percentage) 0.00% 0.00% 0.00%