Commitments (Details)
$ in Thousands
1 Months Ended 12 Months Ended
Dec. 31, 2015
USD ($)
Dec. 31, 2016
USD ($)
Installment
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Summary of minimum annual rental commitments [Abstract]        
2017   $ 4,213    
2018   3,936    
2019   3,565    
2020   2,345    
2021   3,777    
Total   17,836    
Rent Expense   $ 7,613 $ 7,730 $ 8,738
Extraordinary dividend declared $ 21,000      
Extraordinary dividend special tax rate 15.00%      
Proceeds from association a special distribution     $ 1,672  
Number of installments for dividend receivable in 2016 | Installment   3