Summary of Amounts Reclassification from AOCI to Net Income (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of pension and other employee benefits items Actuarial losses and other reclassified from AOCI to net income, before tax	[1]	$ (33)	$ (50)
Amortization of pension and other employee benefits items Actuarial losses and other reclassified from AOCI to net income, tax benefit	[1]	11	15
Amortization of pension and other employee benefits items Actuarial losses and other reclassified from AOCI to net income, net of tax	[1],[2]	(22)	(35)
Gains on hedging activities reclassified from AOCI to net income, before tax	[1]	5	25
Gains on hedging activities reclassified from AOCI to net income, tax expense	[1]	(2)	(9)
Gains on hedging activities reclassified from AOCI to net income, net of tax	[1],[2]	3	16
Gains on available for sale securities reclassified from AOCI to net income, before tax	[1]	3,388	(9)
Gains on available for sale securities reclassified from AOCI to net income, tax benefit	[1]		2
Available-for-sale securities reclassified from AOCI to net income, net of tax	[1],[2]	3,388	(7)
Total reclassification for the period	[1],[2]	3,369	(26)
Other income, net | Equity securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gains on sale securities sale reclassified from AOCI to net income, before tax	[1]	3,388
Gains on sale securities Other-than-temporary impairment of reclassified from AOCI to net income, before tax	[1]		(9)
Interest rate contract | Net Interest Expense
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gains on hedging activities reclassified from AOCI to net income, before tax	[1]	4
Foreign exchange contract | Cost of Sales
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gains on hedging activities reclassified from AOCI to net income, before tax	[1]	1	25
Actuarial losses and other
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of pension and other employee benefits items Actuarial losses and other reclassified from AOCI to net income, before tax	[1],[3]	$ (33)	$ (50)

[1] Amounts in parentheses indicate reductions to net income.

[2] See table below for details about these reclassifications.

[3] These AOCI components are included in the computation of net periodic benefit cost disclosed in Note 10.