Changes in Balance of Accumulated Other Comprehensive Loss, Net of Income Taxes (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		$ 3,097		$ 3,400		$ 4,918
Other comprehensive loss before reclassifications		(1,232)		(424)		(2,973)
Amounts reclassified from AOCL
Recognition of net actuarial losses		938		1,109		806
Amortization of net prior service credits		(239)		(259)		(100)
Recognition of net prior service credits from divestiture of IS&GS segment	[1]	(134)
Other		9	[1]			(2)
Total reclassified from AOCL		574		850		704
Other comprehensive (loss) income, net of tax		(658)		426		(2,269)
Ending Balance		1,606		3,097		3,400
Postretirement Benefit Plan Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(11,314)		(11,813)	[2]	(9,649)	[2]
Other comprehensive loss before reclassifications		(1,232)		(351)		(2,870)
Amounts reclassified from AOCL
Recognition of net actuarial losses		938		1,109		806
Amortization of net prior service credits		(239)		(259)		(100)
Recognition of net prior service credits from divestiture of IS&GS segment	[1]	(134)
Total reclassified from AOCL		565		850		706
Other comprehensive (loss) income, net of tax		(667)		499		(2,164)
Ending Balance		(11,981)	[2]	(11,314)		(11,813)	[2]
Other, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(130)		(57)	[2]	48	[2]
Other comprehensive loss before reclassifications				(73)		(103)
Amounts reclassified from AOCL
Other		9	[1]			(2)
Total reclassified from AOCL		9				(2)
Other comprehensive (loss) income, net of tax		9		(73)		(105)
Ending Balance		(121)	[2]	(130)		(57)	[2]
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(11,444)		(11,870)	[2]	(9,601)	[2]
Amounts reclassified from AOCL
Other comprehensive (loss) income, net of tax		(658)		426		(2,269)
Ending Balance		$ (12,102)	[2]	$ (11,444)		$ (11,870)	[2]

[1] Associated with the divesture of the IS&GS business and included in net gain on divestiture of discontinued operations.

[2] AOCL related to postretirement benefit plans is shown net of tax benefits at December 31, 2016, 2015 and 2014 of $6.5 billion, $6.2 billion and $6.4 billion. These tax benefits include amounts recognized on our income tax returns as current deductions and deferred income taxes, which will be recognized on our tax returns in future years. See "Note 9 - Income Taxes" and "Note 11 -Postretirement Plans" for more information on our income taxes and postretirement benefit plans.