Contingencies Schedule of FCPA Expenses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Foreign Corrupt Practices Act Expenses [Line Items]
Foreign corrupt practices act related expenses	$ 8	$ 12	$ 15	$ 28
Compliance programs and organizational enhancements
Foreign Corrupt Practices Act Expenses [Line Items]
Foreign corrupt practices act related expenses	3	5	7	8
Inquiry and investigation expense
Foreign Corrupt Practices Act Expenses [Line Items]
Foreign corrupt practices act related expenses	$ 5	$ 7	$ 8	$ 20