Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Jul. 27, 2019	Jul. 28, 2018	Jul. 29, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 11,621	$ 110	$ 9,609
Available-for-sale investments:
Change in net unrealized gains and losses, net of tax benefit (expense) of $(101), $(11), and $74 for fiscal 2019, 2018, and 2017, respectively	459	(554)	(89)
Net (gains) losses reclassified into earnings, net of tax expense (benefit) of $6, $104, and $(37) for fiscal 2019, 2018, and 2017, respectively	19	(183)	50
Total Available-for-sale investments	478	(737)	(39)
Cash flow hedging instruments:
Change in unrealized gains and losses, net of tax benefit (expense) of $0, $(3), and $(5) for fiscal 2019, 2018, and 2017, respectively	0	18	17
Net (gains) losses reclassified into earnings, net of tax (benefit) expense of $0, $7, and $(5) for fiscal 2019, 2018, and 2017, respectively	(3)	(61)	74
Total Cash flow hedging instruments	(3)	(43)	91
Net change in cumulative translation adjustment and actuarial gains and losses, net of tax benefit (expense) of $15, $(8), and $(13) for fiscal 2019, 2018, and 2017, respectively	(250)	(160)	321
Other comprehensive income (loss)	225	(940)	373
Comprehensive income (loss)	11,846	(830)	9,982
Comprehensive (income) loss attributable to noncontrolling interests	0	0	(1)
Comprehensive income (loss) attributable to Cisco Systems, Inc.	$ 11,846	$ (830)	$ 9,981