Amounts Recognized on Balance Sheets Related to Qualified Defined Benefit Pension Plans and Retiree Medical and Life Insurance Plans (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss for postretirement benefit plan adjustments, after tax	$ 13,493		$ 11,257		$ 9,010	$ 8,595
Qualified Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss before tax	19,539	[1]	16,075	[1]
Accumulated other comprehensive loss after tax	12,600		10,400
Retiree Medical And Life Insurance Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss before tax	774	[1]	638	[1]
Accumulated other comprehensive loss after tax	500		413
Other Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss before tax	626		596
Accumulated other comprehensive loss after tax	406		385
Postretirement Benefit Plan Adjustments
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss for postretirement benefit plan adjustments, after tax	$ 13,532		$ 11,186		$ 8,994	$ 8,564

[1] Accumulated other comprehensive loss for postretirement benefit plan adjustments, after tax, of $13.5 billion and $11.2 billion at December 31, 2012 and 2011 (Note 1) includes $19.5 billion ($12.6 billion after tax) and $16.1 billion ($10.4 billion after tax) for qualified defined benefit pension plans, $774 million ($500 million after tax) and $638 million ($413 million after tax) for retiree medical and life insurance plans, and $626 million ($406 million after tax) and $596 million ($385 million after tax) for other plans.