Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Share Repurchase Program (Details)

v3.19.1
Summary of Significant Accounting Policies - Share Repurchase Program (Details) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Feb. 28, 2017
Apr. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Open market purchase of treasury shares   $ 1,771,000    
Open market purchase of treasury shares, fees   $ 9,000    
Treasury Stock        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Open market purchase of common shares (in shares) 0 212,131    
Open market purchase of treasury shares   $ 1,771,000    
Common Class A        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock repurchase program, authorized amount (up to)     $ 15,000,000 $ 10,000,000