Annual report pursuant to Section 13 and 15(d)

Income Taxes - Summary of uncertain tax positions (Details 4)

v3.8.0.1
Income Taxes - Summary of uncertain tax positions (Details 4) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]    
Balance, beginning of year $ 674 $ 0
Increase related to prior period positions 0 492
Increase related to current year positions 203 182
Decrease related to prior period positions (192) 0
Balance, end of year $ 685 $ 674