Special Charges (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) aircraft	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) aircraft	Sep. 30, 2015 USD ($)
Property, Plant and Equipment [Line Items]
Payments for Purchase of Other Assets			$ 447,455	$ 451,799
Special charges (credits)	$ 7,355	$ (76)	$ 31,609	$ 673
Aircraft [Member]
Property, Plant and Equipment [Line Items]
Number of Previously Leased Aircraft Purchased | aircraft			6
Airbus A319 [Member] | Aircraft [Member]
Property, Plant and Equipment [Line Items]
Number of Previously Leased Aircraft Purchased | aircraft	3		6
Payments to Acquire Equipment on Lease	$ 58,800		$ 124,700
Payments for Purchase of Other Assets	58,100		91,900
Noncash or Part Noncash Acquisition, Description	700		32,800
Fair Value of Assets Acquired	38,200		79,400
Special charges (credits)	7,355		31,648
Operating Leases, Rent Expense, Supplemental, Maintenance Reserves	$ 13,200		$ 13,700