Schedule of Effect of Four Quarters Events (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected Quarterly Financial Data [Line Items]
Severance and benefit costs	$ 141	$ 6	$ 38	$ 14	$ 91			$ 14	$ 76	$ 199	$ 105	$ 125
Integration-related costs	17	28	17	34	40	50	45	70		96	205	739
Labor agreement costs						127					127	475
Impairment of assets	16		32	1	33					49	33	30
(Gains) losses on sale of assets and other special (gains) losses, net	5	9	16	3	1	34	7	8		33	50	(46)
Total special items					165	211	52	92
Income tax benefit	(6)	(3)		(1)	(7)					(4)	(32)	(1)
Total special items, net of tax					158	211	52	92
Special charges	179	43	169	52						443	520	1,323
Loss on extinguishment of debt and other, net	53			21						74		309
Total operating and nonoperating special charges, net of income taxes	226	40	169	72						507	513	1,312
Permanently grounded Embraer ERJ 135 aircraft
Selected Quarterly Financial Data [Line Items]
Costs associated with permanently grounding Embraer ERJ 135 aircraft			$ 66							$ 66