Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 27, 2019	Apr. 28, 2018	Apr. 27, 2019	Apr. 28, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 3,044	$ 2,691	$ 9,415	$ (3,693)
Available-for-sale investments:
Change in net unrealized gains and losses, net of tax benefit (expense) of $(64) and $(63) for the third quarter and first nine months of fiscal 2019, respectively, and $18 and $(4) for the corresponding periods of fiscal 2018, respectively	232	(428)	319	(624)
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $5 and $4 for the third quarter and first nine months of fiscal 2019, respectively, and $3 and $28 for the corresponding periods of fiscal 2018, respectively	12	(14)	22	(80)
Total- Available-for-sale investments	244	(442)	341	(704)
Cash flow hedging instruments:
Change in unrealized gains and losses, net of tax benefit (expense) of $(2) and $0 for the third quarter and first nine months of fiscal 2019, respectively, and $0 and $(3) for the corresponding periods of fiscal 2018, respectively	10	(10)	3	25
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $0 for each of the third quarter and first nine months of fiscal 2019, and $3 and $7 for the corresponding periods of fiscal 2018, respectively	0	(25)	(1)	(52)
Total- Cash flow hedging instruments	10	(35)	2	(27)
Net change in cumulative translation adjustment and actuarial gains and losses net of tax benefit (expense) of $(1) and $(2) for the third quarter and first nine months of fiscal 2019, respectively, and $3 and $(3) for the corresponding periods of fiscal 2018, respectively	(40)	(255)	(222)	36
Other comprehensive income (loss)	214	(732)	121	(695)
Comprehensive income (loss)	3,258	1,959	9,536	(4,388)
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Cisco Systems, Inc.	$ 3,258	$ 1,959	$ 9,536	$ (4,388)