XML 58 R46.htm IDEA: XBRL DOCUMENT v3.7.0.1
Related party transactions (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Chief Executive Officer (CEO) [Member] | Related Party Transaction, Chartered Aircraft Expenses [Member]      
Related Party Transaction [Line Items]      
Expense for services rendered $ 0.0 $ 0.6  
Director [Member]      
Related Party Transaction [Line Items]      
Expense for services rendered 0.0 $ 0.1  
Accounts payable to related party $ 0.0   $ 0.3