Borrowings - Schedule of Long-Term Debt (Details) - USD ($)	Jan. 31, 2020	Oct. 31, 2019	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	May 31, 2011	Dec. 31, 2010
Long-term debt
Fair value adjustment related to hedged debt	$ 4,000,000	$ 4,000,000
Unamortized debt issuance cost	(15,000,000)	(16,000,000)
Current portion of long-term debt	(878,000,000)	(307,000,000)
Total long-term debt	3,932,000,000	4,780,000,000
U.S. Dollar Global Notes
Long-term debt
Long-term debt	4,247,000,000	4,246,000,000
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
Long-term debt	649,000,000	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
Long-term debt	667,000,000	667,000,000
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
Long-term debt	538,000,000	538,000,000
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
Long-term debt	695,000,000	695,000,000
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
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
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%
Other borrowings at 0.51%-8.42%, due in calendar years 2020-2027
Long-term debt
Other borrowings at 0.51%-8.42%, due in calendar years 2020-2027	$ 574,000,000	$ 853,000,000
Other borrowings at 0.51%-8.42%, due in calendar years 2020-2027 | Minimum
Long-term debt
Interest rate (percent)	0.51%
Other borrowings at 0.51%-8.42%, due in calendar years 2020-2027 | Maximum
Long-term debt
Interest rate (percent)	8.42%