Long-Term Debt Long-Term Debt - Line of Credit Facilities (Details) $ in Millions	Dec. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	$ 2,207
Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	1,500
Pacific Routes Revolving Facility
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	450
Bank revolving credit facilities
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	$ 257