Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Asset impairment (Narrative) (Details)

v3.8.0.1
Asset impairment (Narrative) (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
aircraft
engine
Dec. 31, 2016
USD ($)
aircraft
Dec. 31, 2015
USD ($)
aircraft
engine
Asset Impairment [Line Items]      
Asset impairment charges | $ $ 61,286 $ 81,607 $ 16,335
Number of aircraft impaired | aircraft 13 35 8
Number of engines impaired | engine 2   12
Lease Termination Or Amendment [Member]      
Asset Impairment [Line Items]      
Number of aircraft impaired | aircraft 6 25 4
Number of engines impaired | engine 1    
Part Of Sale Transactions And Classified As Flight Equipment Held For Sale [Member]      
Asset Impairment [Line Items]      
Number of aircraft impaired | aircraft 7 10  
Number of engines impaired | engine 1    
Undiscounted Cash Flows Substantially Do Not Exceed Carrying Value [Member]      
Asset Impairment [Line Items]      
Number of aircraft impaired | aircraft     4
Number of engines impaired | engine     12