Restructuring Charges (Summary of Restructuring Charges) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) airplane	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) airplane	Jun. 30, 2019 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 41,397	$ 0	$ 41,397	$ 0
Number of airplanes held for sale (in airplanes) | airplane	2		2
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 19,867
Pension and termination benefit charges
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	10,913
Contract exit costs and other
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 10,617