Accumulated Other Comprehensive Income and Supplemental Equity Disclosure - Changes in AOCI (Details) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 26, 2018	Oct. 27, 2017	Oct. 26, 2018	Oct. 27, 2017	Apr. 27, 2018	Apr. 28, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance			$ 50,822,000,000	$ 50,416,000,000
Other comprehensive (loss) income	$ (292,000,000)	$ (136,000,000)	(876,000,000)	553,000,000
Cumulative effect of change in accounting principle						$ 296,000,000
Balance	49,714,000,000	51,578,000,000	49,714,000,000	51,578,000,000
Unrealized (Loss) Gain on Investment Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance			(194,000,000)	(69,000,000)
Other comprehensive income (loss) before reclassifications			(19,000,000)	63,000,000
Reclassifications			10,000,000	(8,000,000)
Other comprehensive (loss) income			(9,000,000)	55,000,000
Cumulative effect of change in accounting principle					$ 47,000,000
Balance	(156,000,000)	(14,000,000)	(156,000,000)	(14,000,000)
Other Comprehensive Income (Loss), Tax [Abstract]
Other comprehensive income (loss) before reclassifications, tax expense (benefit)			(1,000,000)	27,000,000
Reclassifications, tax expense (benefit)			0	4,000,000
Cumulative Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance			(268,000,000)	(1,452,000,000)
Other comprehensive income (loss) before reclassifications			(1,252,000,000)	662,000,000
Reclassifications			0	(34,000,000)
Other comprehensive (loss) income			(1,252,000,000)	628,000,000
Cumulative effect of change in accounting principle					0
Balance	(1,520,000,000)	(824,000,000)	(1,520,000,000)	(824,000,000)
Other Comprehensive Income (Loss), Tax [Abstract]
Other comprehensive income (loss) before reclassifications, tax expense (benefit)			(5,000,000)
Net Change in Retirement Obligations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance			(1,117,000,000)	(1,129,000,000)
Other comprehensive income (loss) before reclassifications			0	(19,000,000)
Reclassifications			48,000,000	33,000,000
Other comprehensive (loss) income			48,000,000	14,000,000
Cumulative effect of change in accounting principle					0
Balance	(1,069,000,000)	(1,115,000,000)	(1,069,000,000)	(1,115,000,000)
Other Comprehensive Income (Loss), Tax [Abstract]
Other comprehensive income (loss) before reclassifications, tax expense (benefit)			0	(4,000,000)
Reclassifications, tax expense (benefit)			10,000,000	15,000,000
Unrealized (Loss) Gain on Derivative Financial Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance			(207,000,000)	37,000,000
Other comprehensive income (loss) before reclassifications			343,000,000	(140,000,000)
Reclassifications			(3,000,000)	(4,000,000)
Other comprehensive (loss) income			340,000,000	(144,000,000)
Cumulative effect of change in accounting principle					0
Balance	133,000,000	(107,000,000)	133,000,000	(107,000,000)
Other Comprehensive Income (Loss), Tax [Abstract]
Other comprehensive income (loss) before reclassifications, tax expense (benefit)			100,000,000	(81,000,000)
Reclassifications, tax expense (benefit)			(3,000,000)	4,000,000
Total Accumulated Other Comprehensive (Loss) Income
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance			(1,786,000,000)	(2,613,000,000)
Other comprehensive income (loss) before reclassifications			(928,000,000)	566,000,000
Reclassifications			55,000,000	(13,000,000)
Other comprehensive (loss) income			(873,000,000)	553,000,000
Cumulative effect of change in accounting principle					$ 47,000,000
Balance	$ (2,612,000,000)	$ (2,060,000,000)	$ (2,612,000,000)	$ (2,060,000,000)