v3.19.1
Stock-Based Compensation - Restricted Stock Vesting Schedule (Details) - Restricted Stock - shares
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
2019 18,500    
2020 5,500    
2021 5,500    
2022 5,500    
2023 3,000    
Nonvested restricted stock 38,000 42,000 52,000