Share Repurchases (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Oct. 31, 2018
Feb. 28, 2018
Equity, Class of Treasury Stock [Line Items]          
Value of common stock repurchased $ 23,872 $ 1,821 $ 3,242    
Treasury Stock          
Equity, Class of Treasury Stock [Line Items]          
Number of common stock repurchased (in shares) 937,264 119,007 427,646    
Maximum          
Equity, Class of Treasury Stock [Line Items]          
Common stock authorized for repurchase $ 16,100     $ 20,000 $ 20,000