XML 85 R43.htm IDEA: XBRL DOCUMENT v3.19.1
Cash and cash equivalents (Tables)
12 Months Ended
Dec. 31, 2018
Statements [Line Items]  
Disclosure of detailed information about cash and cash equivalents explanatory [Table Text Block]
    Dec. 31, 2018     Dec. 31, 2017     Jan. 1, 2017  
                   
Cash on hand and demand deposits $  515,497   $  356,499   $  129,850  
Short-term money market instruments with maturities of of three months or less at acquisition date           17,014  
  $  515,497   $  356,499   $  146,864