XML 73 R63.htm IDEA: XBRL DOCUMENT v3.10.0.1
Income taxes (Details)
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2018
Dec. 31, 2017
Income taxes            
Federal statutory rate 12.00% 22.60% 11.80% 21.80% 21.00% 35.00%