Special Items - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2013 Aircraft	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012 Attendant	Dec. 31, 2012 Aircraft
Special Charges [Line Items]
Labor agreement costs		$ 127	$ 454	$ 127	$ 454
Severance and benefits				14	125
Number of flight attendants voluntarily on leave				1,300	1,800
Temporary grounding of 787 aircraft charges				18
Adjustment of reserves for certain legal matters		34
Gain related to contract termination				5
Loss on sale of asset				2
Number of mechanics offering to retire early					400
Number of flight attendants accepted voluntary retirement					1,300
Number of aircraft to be sold	30
Number of aircraft that the company operate						133
Accelerated depreciation recorded on aircraft		31		71
Decrease in net income per basic share		$ 0.09		$ 0.21
Decrease in net income per diluted share		$ 0.08		$ 0.18
Accrual severance and medical costs		29	59	29	59
Accrual balance of future lease		1	6	1	6
International Association Of Machinists
Special Charges [Line Items]
Labor agreement costs		127
Voluntary retirement program
Special Charges [Line Items]
Severance and benefits					$ 76