Restructuring and Other Items - Schedule of Amounts Recorded on Consolidated Statements of Operations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring and other items	$ 716	$ 402	$ 452
Fleet, facilities and other
Restructuring Cost and Reserve [Line Items]
Restructuring and other items	758	402	293
Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring and other items	71	0	237
Routes and slots
Restructuring Cost and Reserve [Line Items]
Restructuring and other items	0	0	(78)
Settlements
Restructuring Cost and Reserve [Line Items]
Restructuring and other items	$ (113)	$ 0	$ 0