Postretirement Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Defined Benefit Plan Disclosure [Line Items]
Recognition of previously deferred postretirement benefit plan amounts, net of tax	$ 212	$ 186	$ 637	$ 520
Recognition of previously deferred postretirement benefit plan amounts, tax	117	102	349	285
Other postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Recognition of previously deferred postretirement benefit plan amounts, before tax	$ 16	13	$ 44	32
Qualified defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Contributions made by the employer		$ 485		$ 1,000