Accrued maintenance liability (Tables)
|12 Months Ended|
Dec. 31, 2017
|Accrued Maintenance Liability [Abstract]|
|Schedule of movements in accrued maintenance liability||
Movements in accrued maintenance liability during the years ended December 31, 2017 and 2016 were as follows:
Schedule Of Movements In Accrued Maintenance Liability [Table Text Block]
No definition available.