Special Charges (Details) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 aircraft	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Special charges, non-operating	$ 0	$ 1,744			$ 0	$ 90,357
Special Charges [Abstract]
Special charges (credits)	$ 0	$ (686)			$ 0	88,656
Airbus A319 [Member] | Capital Lease Obligations [Member]
Special Charges [Abstract]
Purchase price			$ 285,000
Number of aircrafts purchased | aircraft				14
Pilots [Member]
Special Charges [Abstract]
Ratification Incentive						80,200
Adjustments for contractual provisions						8,500
Special charges (credits)						$ 88,700