Aircraft Held for Sale - Narrative (Details)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2015
USD ($)
aircraft
Mar. 31, 2015
USD ($)
aircraft
Dec. 31, 2015
USD ($)
aircraft
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Long Lived Assets Held-for-sale [Line Items]          
Impairment charge on aircraft held for sale | $ $ 8,100 $ 7,100 $ 15,236 $ 0 $ 0
Aircraft          
Long Lived Assets Held-for-sale [Line Items]          
Sale period (in years)     1 year    
Number of aircraft classified as held for sale during period | aircraft 8 9      
Number of aircraft held for sale | aircraft 15   15    
Impairment charge on aircraft held for sale | $     $ 14,859