Segment Information - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Revenue from External Customer [Line Items]
Revenues	$ 1,696	$ 1,502	$ 2,861	$ 2,518
Small Business & Self-Employed
Revenue from External Customer [Line Items]
Revenues	973	833	2,019	1,741
Consumer
Revenue from External Customer [Line Items]
Revenues	499	461	599	551
Strategic Partner
Revenue from External Customer [Line Items]
Revenues	224	208	243	226
Online Ecosystem Subsegment | Small Business & Self-Employed
Revenue from External Customer [Line Items]
Revenues	530	394	1,031	765
Online Ecosystem Subsegment | Small Business & Self-Employed | QuickBooks
Revenue from External Customer [Line Items]
Revenues	330	231	636	448
Online Ecosystem Subsegment | Small Business & Self-Employed | Online Services
Revenue from External Customer [Line Items]
Revenues	200	163	395	317
Desktop Ecosystem Subsegment | Small Business & Self-Employed
Revenue from External Customer [Line Items]
Revenues	443	439	988	976
Desktop Ecosystem Subsegment | Small Business & Self-Employed | QuickBooks
Revenue from External Customer [Line Items]
Revenues	165	154	404	382
Desktop Ecosystem Subsegment | Small Business & Self-Employed | Desktop Services And Supplies
Revenue from External Customer [Line Items]
Revenues	278	285	584	594
Desktop Ecosystem Subsegment | Small Business & Self-Employed | QuickBooks Packaged Software
Revenue from External Customer [Line Items]
Revenues	$ 34	$ 37	$ 61	$ 66