Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Oct. 26, 2019	Oct. 27, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 2,926	$ 3,549
Available-for-sale investments:
Change in net unrealized gains and losses, net of tax benefit (expense) of $(14) and $13 for the first quarter of fiscal 2020 and fiscal 2019, respectively	73	5
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $5 and $0 for the first quarter of fiscal 2020 and fiscal 2019, respectively	(5)	6
Total- Available-for-sale investments	68	11
Cash flow hedging instruments:
Change in unrealized gains and losses, net of tax benefit (expense) of $1 for each of the first quarter of fiscal 2020 and fiscal 2019	0
Change in unrealized gains and losses, net of tax benefit (expense) of $1 for each of the first quarter of fiscal 2020 and fiscal 2019		(3)
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $0 for each of the first quarter of fiscal 2020 and fiscal 2019	0
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $0 for each of the first quarter of fiscal 2020 and fiscal 2019		0
Total- Cash flow hedging instruments	0
Total- Cash flow hedging instruments		(3)
Net change in cumulative translation adjustment and actuarial gains and losses net of tax benefit (expense) of $0 and $(1) for the first quarter of fiscal 2020 and fiscal 2019, respectively	(91)	(209)
Other comprehensive loss	(23)	(201)
Comprehensive income	2,903	3,348
Comprehensive (income) loss attributable to noncontrolling interests	0	0
Comprehensive income attributable to Cisco Systems, Inc.	$ 2,903	$ 3,348