Contingencies Schedule of FCPA Expenses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Foreign Corrupt Practices Act Expenses [Line Items]
Foreign corrupt practices act related expenses	$ 12	$ 28	$ 28	$ 53
Compliance programs and organizational enhancements
Foreign Corrupt Practices Act Expenses [Line Items]
Foreign corrupt practices act related expenses	5	5	8	9
Inquiry and investigation expense
Foreign Corrupt Practices Act Expenses [Line Items]
Foreign corrupt practices act related expenses	$ 7	$ 23	$ 20	$ 44