Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Oct. 27, 2018	Oct. 28, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 3,549	$ 2,394
Available-for-sale investments:
Change in net unrealized gains and losses, net of tax benefit (expense) of $13 and $(23) for the three months ended October 27, 2018 and October 28, 2017, respectively	5	(5)
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $0 and $10 for the three months ended October 27, 2018 and October 28, 2017, respectively	6	(23)
Total- Available-for-sale investments	11	(28)
Cash flow hedging instruments:
Change in unrealized gains and losses, net of tax benefit (expense) of $1 and $(1) for the three months ended October 27, 2018 and October 28, 2017, respectively	(3)	7
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $0 and $2 for the three months ended October 27, 2018 and October 28, 2017, respectively	0	(11)
Total- Cash flow hedging instruments	(3)	(4)
Net change in cumulative translation adjustment and actuarial gains and losses net of tax benefit (expense) of $(1) and $(2) for the three months ended October 27, 2018 and October 28, 2017, respectively	(209)	17
Other comprehensive income (loss)	(201)	(15)
Comprehensive income (loss)	3,348	2,379
Comprehensive (income) loss attributable to noncontrolling interests	0	0
Comprehensive income (loss) attributable to Cisco Systems, Inc.	$ 3,348	$ 2,379