Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 28, 2018	Apr. 29, 2017	Apr. 28, 2018	Apr. 29, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 2,691	$ 2,515	$ (3,693)	$ 7,185
Available-for-sale investments:
Change in net unrealized gains and losses, net of tax benefit (expense) of $18 and $(4) for the three and nine months ended April 28, 2018, respectively, and $(25) and $129 for the corresponding periods of fiscal 2017, respectively	(428)	229	(624)	(168)
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $3 and $28 for the three and nine months ended April 28, 2018, respectively, and $(32) and $(38) for the corresponding periods of fiscal 2017, respectively	(14)	44	(80)	53
Total- Available-for-sale investments	(442)	273	(704)	(115)
Cash flow hedging instruments:
Change in unrealized gains and losses, net of tax benefit (expense) of $0 and $(3) for the three and nine months ended April 28, 2018, respectively, and $(5) and $(1) for the corresponding periods of fiscal 2017, respectively	(10)	20	25	(24)
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $3 and $7 for the three and nine months ended April 28, 2018, respectively, and $(2) and $(5) for the corresponding periods of fiscal 2017, respectively	(25)	25	(52)	61
Total- Cash flow hedging instruments	(35)	45	(27)	37
Net change in cumulative translation adjustment and actuarial gains and losses net of tax benefit (expense) of $3 and $(3) for the three and nine months ended April 28, 2018, respectively, and $(6) and $(7) for the corresponding periods of fiscal 2017, respectively	(255)	134	36	63
Other comprehensive income (loss)	(732)	452	(695)	(15)
Comprehensive income (loss)	1,959	2,967	(4,388)	7,170
Comprehensive (income) loss attributable to noncontrolling interests	0	7	0	(1)
Comprehensive income (loss) attributable to Cisco Systems, Inc.	$ 1,959	$ 2,974	$ (4,388)	$ 7,169