Schedule of Debt Outstanding (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt and capital lease obligations	[1]	$ 2,782	$ 4,732
Current portion	[1]	(3)	(810)
Long-term portion	[1]	$ 2,779	3,922
Variable-rate loan due 2020
Debt Instrument [Line Items]
Effective Interest Rate	[2]	1.00%
Debt and capital lease obligations	[1]	$ 294	281
5.9% notes due 2016
Debt Instrument [Line Items]
Effective Interest Rate	[2]	5.80%
Debt and capital lease obligations	[1]		301
0.95% notes due 2016
Debt Instrument [Line Items]
Effective Interest Rate	[2]	1.20%
Debt and capital lease obligations	[1]		500
1.85% Notes due 2017
Debt Instrument [Line Items]
Effective Interest Rate	[2]	2.10%
Debt and capital lease obligations	[1]		499
5.375% notes due 2018
Debt Instrument [Line Items]
Effective Interest Rate	[2]	5.70%
Debt and capital lease obligations	[1]		501
1.85% notes due 2018
Debt Instrument [Line Items]
Effective Interest Rate	[2]	2.10%
Debt and capital lease obligations	[1]		747
4.5% notes due 2019
Debt Instrument [Line Items]
Effective Interest Rate	[2]	4.50%
Debt and capital lease obligations	[1]		530
4.25% notes due 2020
Debt Instrument [Line Items]
Effective Interest Rate	[2]	4.20%
Debt and capital lease obligations	[1]		299
1.7% notes due 2021
Debt Instrument [Line Items]
Effective Interest Rate	[2]	1.60%
Debt and capital lease obligations	[1]	$ 397
2.40% notes due 2022
Debt Instrument [Line Items]
Effective Interest Rate	[2]	2.50%
Debt and capital lease obligations	[1]	$ 208	211
3.2% notes due 2023
Debt Instrument [Line Items]
Effective Interest Rate	[2]	3.10%
Debt and capital lease obligations	[1]		146
2.6% notes due 2026
Debt Instrument [Line Items]
Effective Interest Rate	[2]	2.20%
Debt and capital lease obligations	[1]	$ 744
7.65% Debentures due 2027
Debt Instrument [Line Items]
Effective Interest Rate	[2]	7.70%
Debt and capital lease obligations	[1]	$ 5	5
6.625% Debentures due 2028
Debt Instrument [Line Items]
Effective Interest Rate	[2]	6.70%
Debt and capital lease obligations	[1]	$ 99	100
6.25% notes due 2037
Debt Instrument [Line Items]
Effective Interest Rate	[2]	5.80%
Debt and capital lease obligations	[1]	$ 265	265
3.65% Notes due 2042
Debt Instrument [Line Items]
Effective Interest Rate	[2]	3.70%
Debt and capital lease obligations	[1]	$ 6	6
4.5% notes due 2043
Debt Instrument [Line Items]
Effective Interest Rate	[2]	4.50%
Debt and capital lease obligations	[1]	$ 255	255
3.5% notes due 2046
Debt Instrument [Line Items]
Effective Interest Rate	[2]	3.00%
Debt and capital lease obligations	[1]	$ 439
Other
Debt Instrument [Line Items]
Debt and capital lease obligations	[1]	$ 70	$ 86

[1] Book values include any discounts, premiums and adjustments related to hedging instruments.

[2] Excludes the effect of any related interest rate swaps.