Summary of Significant Accounting Policies - Derivative Instruments (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($) aircraft derivative_instrument
2015 | Airbus A321
Derivative [Line Items]
Number of aircraft protected by interest rate derivatives scheduled for delivery | aircraft	3
Interest rate swap
Derivative [Line Items]
Number of interest rate derivatives settled | derivative_instrument	6
Notional amount | $	$ 120