Share Repurchases (Details) - USD ($)
$ in Thousands
6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
May 31, 2015
Equity, Class of Treasury Stock [Line Items]      
Common stock authorized for repurchase $ 5,900    
Number of common stock repurchased (in shares) 119,007 427,646  
Value of common stock repurchased $ 1,821 $ 3,242  
Maximum      
Equity, Class of Treasury Stock [Line Items]      
Common stock authorized for repurchase     $ 20,000