Supplemental Financial Information - Accounts Payable (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accounts Payable [Abstract]
Accounts payable trade	$ 178	$ 123
Salaries payable	173	160
Taxes payable	179	163
Aircraft maintenance payable	168	314
Fuel payable	48	85
Other payable	442	358
Accounts payable	$ 1,188	$ 1,203