Changes in Balance of Accumulated Other Comprehensive Loss, Net of Income Taxes (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 25, 2017	Jun. 26, 2016	Jun. 25, 2017		Jun. 26, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance				$ 1,606		$ 3,097
Other comprehensive income (loss) before reclassifications				56		(7)
Amounts reclassified from AOCL
Recognition of net actuarial losses	[1]			516		469
Amortization of net prior service credits	[1]			(114)		(123)
Other				7		1
Total reclassified from AOCL				409		347
Other comprehensive income, net of tax		$ 255	$ 150	465		340
Ending Balance		1,349	2,997	1,349		2,997
Postretirement Benefit Plan Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance				(11,981)		(11,314)
Other comprehensive income (loss) before reclassifications				3
Amounts reclassified from AOCL
Recognition of net actuarial losses		258	235	516	[1]	469	[1]
Amortization of net prior service credits		(58)	(62)	(114)	[1]	(123)	[1]
Total reclassified from AOCL		200	173	402		346
Other comprehensive income, net of tax				405		346
Ending Balance		(11,576)	(10,968)	(11,576)		(10,968)
Other, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance				(121)		(130)
Other comprehensive income (loss) before reclassifications				53		(7)
Amounts reclassified from AOCL
Other				7		1
Total reclassified from AOCL				7		1
Other comprehensive income, net of tax				60		(6)
Ending Balance		(61)	(136)	(61)		(136)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance				(12,102)		(11,444)
Amounts reclassified from AOCL
Other comprehensive income, net of tax				465		340
Ending Balance		$ (11,637)	$ (11,104)	$ (11,637)		$ (11,104)

[1] Reclassifications from AOCL related to our postretirement benefit plans were recorded as a component of net periodic benefit cost for each period presented (see "Note 6 - Postretirement Plans"). These amounts include $200 million and $173 million, net of tax, for the quarters ended June 25, 2017 and June 26, 2016, which are comprised of the recognition of net actuarial losses of $258 million and $235 million for the quarters ended June 25, 2017 and June 26, 2016 and the amortization of net prior service credits of $(58) million and $(62) million for the quarters ended June 25, 2017 and June 26, 2016.