v3.8.0.1
Cash and cash equivalents (Details) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Mar. 31, 2017
Dec. 31, 2016
Cash and cash equivalents:        
Cash $ 16,290 $ 24,430    
Money market accounts 2,262 2,255    
Total cash and cash equivalents $ 18,552 $ 26,685 $ 18,978 $ 19,485