Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 26, 2019	Jan. 27, 2018	Jan. 26, 2019	Jan. 27, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 2,822	$ (8,778)	$ 6,371	$ (6,384)
Available-for-sale investments:
Change in net unrealized gains and losses, net of tax benefit (expense) of $(12) and $1 for the second quarter and first six months of fiscal 2019, respectively, and $1 and $(22) for the corresponding periods of fiscal 2018, respectively	82	(191)	87	(196)
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $(1) for each of the second quarter and first six months of fiscal 2019, respectively, and $15 and $25 for the corresponding periods of fiscal 2018, respectively	4	(43)	10	(66)
Total- Available-for-sale investments	86	(234)	97	(262)
Cash flow hedging instruments:
Change in unrealized gains and losses, net of tax benefit (expense) of $1 and $2 for the second quarter and first six months of fiscal 2019, respectively, and $(2) and $(3) for the corresponding periods of fiscal 2018, respectively	(4)	28	(7)	35
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $0 for each of the second quarter and first six months of fiscal 2019, respectively, and $2 and $4 for the corresponding periods of fiscal 2018, respectively	(1)	(16)	(1)	(27)
Total- Cash flow hedging instruments	(5)	12	(8)	8
Net change in cumulative translation adjustment and actuarial gains and losses net of tax benefit (expense) of $0 and $(1) for the second quarter and first six months of fiscal 2019, respectively, and $(4) and $(6) for the corresponding periods of fiscal 2018, respectively	27	274	(182)	291
Other comprehensive income (loss)	108	52	(93)	37
Comprehensive income (loss)	2,930	(8,726)	6,278	(6,347)
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Cisco Systems, Inc.	$ 2,930	$ (8,726)	$ 6,278	$ (6,347)