Financial Instruments - Investments by Category and Related Balance Sheet Classification (Details) - USD ($) $ in Millions	Jul. 28, 2017	Apr. 28, 2017
Total available-for sale securities and investments measured at net asset value:
Cost	$ 8,621	$ 9,008
Unrealized Gains	139	127
Unrealized Losses	(217)	(246)
Fair Value	8,543	8,889
Cost method, equity method, and other investments:
Cost	627	589
Total investments [Abstract]
Cost	9,248	9,597
Unrealized Gains	139	127
Unrealized Losses	(217)	(246)
Fair Value	8,543	8,889
Investments
Total available-for sale securities and investments measured at net asset value:
Fair Value	8,397	8,741
Cost method, equity method, and other investments:
Cost	0	0
Total investments [Abstract]
Fair Value	8,397	8,741
Other Assets
Total available-for sale securities and investments measured at net asset value:
Fair Value	146	148
Cost method, equity method, and other investments:
Cost	627	589
Total investments [Abstract]
Fair Value	773	737
Level 1
Available-for-sale securities:
Cost	708	671
Unrealized Gains	49	51
Unrealized Losses	(6)	(9)
Fair Value	751	713
Level 1 \| Investments
Available-for-sale securities:
Fair Value	650	610
Level 1 \| Other Assets
Available-for-sale securities:
Fair Value	101	103
Level 2
Available-for-sale securities:
Cost	7,368	7,792
Unrealized Gains	90	76
Unrealized Losses	(202)	(228)
Fair Value	7,256	7,640
Level 2 \| Investments
Available-for-sale securities:
Fair Value	7,256	7,640
Level 2 \| Other Assets
Available-for-sale securities:
Fair Value	0	0
Level 3
Available-for-sale securities:
Cost	48	48
Unrealized Gains	0	0
Unrealized Losses	(3)	(3)
Fair Value	45	45
Cost method, equity method, and other investments:
Cost	627	589
Level 3 \| Investments
Available-for-sale securities:
Fair Value	0	0
Cost method, equity method, and other investments:
Cost	0	0
Level 3 \| Other Assets
Available-for-sale securities:
Fair Value	45	45
Cost method, equity method, and other investments:
Cost	627	589
Corporate debt securities \| Level 2
Available-for-sale securities:
Cost	4,157	4,643
Unrealized Gains	73	62
Unrealized Losses	(18)	(23)
Fair Value	4,212	4,682
Corporate debt securities \| Level 2 \| Investments
Available-for-sale securities:
Fair Value	4,212	4,682
Corporate debt securities \| Level 2 \| Other Assets
Available-for-sale securities:
Fair Value	0	0
Corporate debt securities \| Level 3
Available-for-sale securities:
Cost	1	1
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	1	1
Corporate debt securities \| Level 3 \| Investments
Available-for-sale securities:
Fair Value	0	0
Corporate debt securities \| Level 3 \| Other Assets
Available-for-sale securities:
Fair Value	1	1
U.S. government and agency securities \| Level 1
Available-for-sale securities:
Cost	653	613
Unrealized Gains	1	2
Unrealized Losses	(4)	(5)
Fair Value	650	610
U.S. government and agency securities \| Level 1 \| Investments
Available-for-sale securities:
Fair Value	650	610
U.S. government and agency securities \| Level 1 \| Other Assets
Available-for-sale securities:
Fair Value	0	0
U.S. government and agency securities \| Level 2
Available-for-sale securities:
Cost	854	860
Unrealized Gains	0	0
Unrealized Losses	(9)	(10)
Fair Value	845	850
U.S. government and agency securities \| Level 2 \| Investments
Available-for-sale securities:
Fair Value	845	850
U.S. government and agency securities \| Level 2 \| Other Assets
Available-for-sale securities:
Fair Value	0	0
Marketable equity securities \| Other Assets
Available-for-sale securities:
Fair Value	101	103
Marketable equity securities \| Level 1
Available-for-sale securities:
Cost	55	58
Unrealized Gains	48	49
Unrealized Losses	(2)	(4)
Fair Value	101	103
Marketable equity securities \| Level 1 \| Investments
Available-for-sale securities:
Fair Value	0	0
Marketable equity securities \| Level 1 \| Other Assets
Available-for-sale securities:
Fair Value	101	103
Mortgage-backed securities \| Level 2
Available-for-sale securities:
Cost	804	766
Unrealized Gains	9	9
Unrealized Losses	(16)	(16)
Fair Value	797	759
Mortgage-backed securities \| Level 2 \| Investments
Available-for-sale securities:
Fair Value	797	759
Mortgage-backed securities \| Level 2 \| Other Assets
Available-for-sale securities:
Fair Value	0	0
Foreign government and agency securities \| Level 2
Available-for-sale securities:
Cost	49	49
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	49	49
Foreign government and agency securities \| Level 2 \| Investments
Available-for-sale securities:
Fair Value	49	49
Foreign government and agency securities \| Level 2 \| Other Assets
Available-for-sale securities:
Fair Value	0	0
Other asset-backed securities \| Level 2
Available-for-sale securities:
Cost	258	228
Unrealized Gains	1	1
Unrealized Losses	(1)	(1)
Fair Value	258	228
Other asset-backed securities \| Level 2 \| Investments
Available-for-sale securities:
Fair Value	258	228
Other asset-backed securities \| Level 2 \| Other Assets
Available-for-sale securities:
Fair Value	0	0
Debt funds
Investments measured at net asset value:
Cost	497	497
Unrealized Gains	0	0
Unrealized Losses	(6)	(6)
Fair Value	491	491
Debt funds \| Investments
Investments measured at net asset value:
Fair Value	491	491
Debt funds \| Other Assets
Investments measured at net asset value:
Fair Value	0	0
Debt funds \| Level 2
Available-for-sale securities:
Cost	1,246	1,246
Unrealized Gains	7	4
Unrealized Losses	(158)	(178)
Fair Value	1,095	1,072
Debt funds \| Level 2 \| Investments
Available-for-sale securities:
Fair Value	1,095	1,072
Debt funds \| Level 2 \| Other Assets
Available-for-sale securities:
Fair Value	0	0
Auction rate securities \| Level 3
Available-for-sale securities:
Cost	47	47
Unrealized Gains	0	0
Unrealized Losses	(3)	(3)
Fair Value	44	44
Auction rate securities \| Level 3 \| Investments
Available-for-sale securities:
Fair Value	0	0
Auction rate securities \| Level 3 \| Other Assets
Available-for-sale securities:
Fair Value	$ 44	$ 44

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