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

Maintenance rights intangible and lease premium, net (Estimated future amortization expense for lease premium) (Details)

v3.8.0.1
Maintenance rights intangible and lease premium, net (Estimated future amortization expense for lease premium) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]    
2018 $ 24,870  
2019 21,176  
2020 21,176  
2021 21,176  
2022 21,176  
Thereafter 177,238  
Finite-lived intangible assets 286,812 $ 317,988
Lease Premiums [Member]    
Finite-Lived Intangible Assets [Line Items]    
2018 11,219  
2019 10,466  
2020 7,727  
2021 5,394  
2022 914  
Thereafter 1,539  
Finite-lived intangible assets $ 37,259 $ 50,891