Summary of Significant Accounting Policies (Detail) - USD ($) $ in Millions	Sep. 30, 2016		Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction in other current assets	$ (347)		$ (573)
Reduction in short-term debt	(788)	[1]	(32)
Reduction in other assets	(2,203)		(2,268)
Reduction in long-term debt	$ (15,090)		(15,636)
Accounting Standards Update 2015-03 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction in other current assets			1
Reduction in short-term debt			1
Reduction in other assets			82
Reduction in long-term debt			$ 82

[1] Short-term debt includes $750 million of 6.375% Senior Notes due September 2017. In October 2016, the Company provided notice of its intent to redeem the notes prior to year end.