Business Combinations (Pro Forma Information) (Details) - MuleSoft - USD ($) $ in Millions	3 Months Ended		6 Months Ended	9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2018	Oct. 31, 2017
Business Acquisition [Line Items]
Total revenues			$ 250
Pretax loss			$ (208)
Total revenues	$ 3,392	$ 2,815		$ 9,763	$ 7,909
Pretax income (loss)	148	43		744	(219)
Net income (loss)	$ 125	$ 5		$ 611	$ (129)