Marketable Securities (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 26, 2015	May. 01, 2016	Jan. 31, 2016
Summary of cash equivalents and marketable securities:
Amortized Cost		$ 4,234	$ 4,672
Unrealized Gain		10	6
Unrealized Loss		(3)	(5)
Estimated Fair Value		4,241	4,673
Classified as:
Cash equivalents		34	232
Marketable securities		4,207	4,441
Total cash equivalents and marketable securities		4,241	4,673
Amortized Cost
Less than one year		1,714	1,619
Due in 1-5 years		2,474	3,019
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date		46	34
Total		4,234	4,672
Estimated Fair Value
Less than one year		1,716	1,619
Due in 1-5 years		2,479	3,020
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date		46	34
Total		4,241	4,673
Net realized gain
Realized Investment Gains	$ 3
Unrealized Loss Position, Fair Value
Unrealized Loss, Less than Twelve Months, Fair Value		482
Unrealized Loss, Twelve Months or Longer, Fair Value		142
Unrealized Loss, Fair Value		624
Unrealized Loss Position, Aggregate Losses
Unrealized Loss, Less than 12 Months, Accumulated Loss		(2)
Unrealized Loss, 12 Months or Longer, Accumulated Loss		0
Unrealized Loss, Accumulated Loss		(2)
Corporate debt securities
Summary of cash equivalents and marketable securities:
Amortized Cost		1,791	1,903
Unrealized Gain		3	1
Unrealized Loss		(1)	(3)
Estimated Fair Value		1,793	1,901
Classified as:
Cash equivalents		3	51
Total cash equivalents and marketable securities		1,793	1,901
Unrealized Loss Position, Fair Value
Unrealized Loss, Less than Twelve Months, Fair Value		422
Unrealized Loss, Twelve Months or Longer, Fair Value		108
Unrealized Loss, Fair Value		530
Unrealized Loss Position, Aggregate Losses
Unrealized Loss, Less than 12 Months, Accumulated Loss		(1)
Unrealized Loss, 12 Months or Longer, Accumulated Loss		0
Unrealized Loss, Accumulated Loss		(1)
Debt securities of United States government agencies
Summary of cash equivalents and marketable securities:
Amortized Cost		1,027	1,170
Unrealized Gain		1	1
Unrealized Loss		0	(1)
Estimated Fair Value		1,028	1,170
Classified as:
Total cash equivalents and marketable securities		1,028	1,170
Debt securities issued by the United States Treasury
Summary of cash equivalents and marketable securities:
Amortized Cost		716	800
Unrealized Gain		2	1
Unrealized Loss		0	0
Estimated Fair Value		718	801
Classified as:
Total cash equivalents and marketable securities		718	801
Asset-backed Securities
Summary of cash equivalents and marketable securities:
Amortized Cost		187	435
Unrealized Gain		3	0
Unrealized Loss		(2)	0
Estimated Fair Value		188	435
Classified as:
Total cash equivalents and marketable securities		188	435
Mortgage backed securities issued by United Sates government-sponsored enterprises
Summary of cash equivalents and marketable securities:
Amortized Cost		380	229
Unrealized Gain		1	3
Unrealized Loss		0	(1)
Estimated Fair Value		381	231
Classified as:
Total cash equivalents and marketable securities		381	231
Unrealized Loss Position, Fair Value
Unrealized Loss, Less than Twelve Months, Fair Value		60
Unrealized Loss, Twelve Months or Longer, Fair Value		34
Unrealized Loss, Fair Value		94
Unrealized Loss Position, Aggregate Losses
Unrealized Loss, Less than 12 Months, Accumulated Loss		(1)
Unrealized Loss, 12 Months or Longer, Accumulated Loss		0
Unrealized Loss, Accumulated Loss		(1)
Foreign government bonds
Summary of cash equivalents and marketable securities:
Amortized Cost		102	92
Unrealized Gain		0	0
Unrealized Loss		0	0
Estimated Fair Value		102	92
Classified as:
Total cash equivalents and marketable securities		102	92
Money market funds
Summary of cash equivalents and marketable securities:
Amortized Cost		31	43
Unrealized Gain		0	0
Unrealized Loss		0	0
Estimated Fair Value		31	43
Classified as:
Total cash equivalents and marketable securities		$ 31	$ 43