Borrowings - Schedule of Long-Term Debt (Details) - USD ($)	1 Months Ended
	Jan. 31, 2014	Apr. 30, 2017	Oct. 31, 2016	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	May 31, 2011	Dec. 31, 2010
Long-term debt
Total long-term debt		$ 6,710,000,000	$ 6,735,000,000
Fair value adjustment related to hedged debt		23,000,000	72,000,000
Less: unamortized debt issuance cost		(21,000,000)	(23,000,000)
Less: current portion of long-term debt		(76,000,000)	(51,000,000)
U.S. Dollar Global Notes
Long-term debt
Total long-term debt		6,493,000,000	6,493,000,000
2009 Shelf Registration Statement- $1,350 issued at discount to par at a price of 99.827% in December 2010 at 3.75%, due December 2020
Long-term debt
Total long-term debt		648,000,000	648,000,000
Face amount of debt instrument								$ 1,350,000,000
Discount to par (percent)								99.827%
Interest rate (percent)								3.75%
2009 Shelf Registration Statement- $1,250 issued at discount to par at a price of 99.799% in May 2011 at 4.3%, due June 2021
Long-term debt
Total long-term debt		1,248,000,000	1,248,000,000
Face amount of debt instrument							$ 1,250,000,000
Discount to par (percent)							99.799%
Interest rate (percent)							4.30%
2009 Shelf Registration Statement- $1,000 issued at discount to par at a price of 99.816% in September 2011 at 4.375%, due September 2021
Long-term debt
Total long-term debt		999,000,000	999,000,000
Face amount of debt instrument						$ 1,000,000,000
Discount to par (percent)						99.816%
Interest rate (percent)						4.375%
2009 Shelf Registration Statement- $1,500 issued at discount to par at a price of 99.707% in December 2011 at 4.65%, due December 2021
Long-term debt
Total long-term debt		1,498,000,000	1,498,000,000
Face amount of debt instrument					$ 1,500,000,000
Discount to par (percent)					99.707%
Interest rate (percent)					4.65%
2009 Shelf Registration Statement- $500 issued at discount to par at a price of 99.771% in March 2012 at 4.05%, due September 2022
Long-term debt
Total long-term debt		499,000,000	499,000,000
Face amount of debt instrument				$ 500,000,000
Discount to par (percent)				99.771%
Interest rate (percent)				4.05%
2009 Shelf Registration Statement- $1,200 issued at discount to par at a price of 99.863% in September 2011 at 6.0%, due September 2041
Long-term debt
Total long-term debt		1,199,000,000	1,199,000,000
Face amount of debt instrument						$ 1,200,000,000
Discount to par (percent)						99.863%
Interest rate (percent)						6.00%
2012 Shelf Registration Statement- $750 issued at par in January 2014 at three-month USD LIBOR plus 0.94%, due January 2019
Long-term debt
Total long-term debt		102,000,000	102,000,000
Face amount of debt instrument	$ 750,000,000
Spread on reference interest rate (percent)	0.94%
2012 Shelf Registration Statement- $1,250 issued at discount to par at a price of 99.954% in January 2014 at 2.75%, due January 2019
Long-term debt
Total long-term debt		300,000,000	300,000,000
Face amount of debt instrument	$ 1,250,000,000
Discount to par (percent)	99.954%
Interest rate (percent)	2.75%
Other, including capital lease obligations, at 0.51%-8.50%, due in calendar years 2017-2025
Long-term debt
Other, including capital lease obligations, at 0.51%-8.50%, due in calendar years 2017-2025		$ 291,000,000	$ 244,000,000
Minimum | Other, including capital lease obligations, at 0.51%-8.50%, due in calendar years 2017-2025
Long-term debt
Interest rate (percent)		0.51%
Maximum | Other, including capital lease obligations, at 0.51%-8.50%, due in calendar years 2017-2025
Long-term debt
Interest rate (percent)		8.50%