v3.6.0.2
Commitments and contingencies - Notes payable and Letters of credit (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
USD ($)
item
Dec. 31, 2015
USD ($)
Future payments    
Current portion of notes payable $ 1,123 $ 151
Non-current portion of notes payable $ 1,661 $ 119
Letter of Credit    
Commitments and contingencies    
Term period of notes payable or Letters of Credit agreements 1 year  
Letters of credit    
Current issued borrowing capacity $ 3,840  
Number of drafts drawn under Letters of Credit | item 0  
Notes payable    
Commitments and contingencies    
Term period of notes payable or Letters of Credit agreements 3 years  
Future payments    
2017 $ 1,123  
2018 1,109  
2019 552  
Total $ 2,784  
Notes payable | Minimum    
Notes Payable    
Interest rates for outstanding notes payable 2.00%  
Notes payable | Maximum    
Notes Payable    
Interest rates for outstanding notes payable 4.80%