XML 60 R49.htm IDEA: XBRL DOCUMENT v3.19.1
Stock-Based Compensation - Summary of Compensation Expense by Type of Award (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Total stock-based compensation $ 773 $ 736
Stock Options [Member]    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Total stock-based compensation 533 593
ESPP [Member]    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Total stock-based compensation $ 240 $ 143