Marketable Securities (Details) - USD ($) $ in Millions | 9 Months Ended | |
Oct. 25, 2015 | Jan. 25, 2015 |
Summary of cash equivalents and marketable securities: | | |
Available-for-sale Securities, Amortized Cost Basis | $ 4,348 | $ 4,413 |
Unrealized Gain | 8 | 11 |
Unrealized Loss | (3) | (3) |
Estimated Fair Value | 4,353 | 4,421 |
Classified as: | | |
Cash equivalents | 96 | 295 |
Marketable securities | 4,257 | 4,126 |
Total cash equivalents and marketable securities | 4,353 | 4,421 |
Amortized Cost | | |
Less than one year | 1,453 | 1,570 |
Due in 1-5 years | 2,811 | 2,720 |
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date | 84 | 123 |
Total | 4,348 | 4,413 |
Estimated Fair Value | | |
Less than one year | 1,454 | 1,571 |
Due in 1-5 years | 2,815 | 2,726 |
Mortgage-backed securities issued by government-sponsored enterprises not due to a single maturity date | 84 | 124 |
Total | 4,353 | 4,421 |
Net realized gain | | |
Realized Investment Gains | 3 | |
Unrealized Loss Position, Fair Value | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 871 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 80 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 951 | |
Unrealized Loss Position, Aggregate Losses | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (3) | |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (3) | |
Corporate debt securities | | |
Summary of cash equivalents and marketable securities: | | |
Available-for-sale Securities, Amortized Cost Basis | 1,975 | 2,185 |
Unrealized Gain | 2 | 2 |
Unrealized Loss | (2) | (1) |
Estimated Fair Value | 1,975 | 2,186 |
Classified as: | | |
Cash equivalents | 51 | 147 |
Total cash equivalents and marketable securities | 1,975 | 2,186 |
Unrealized Loss Position, Fair Value | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 798 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 54 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 852 | |
Unrealized Loss Position, Aggregate Losses | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (2) | |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (2) | |
Debt securities of United States government agencies | | |
Summary of cash equivalents and marketable securities: | | |
Available-for-sale Securities, Amortized Cost Basis | 994 | 750 |
Unrealized Gain | 1 | 1 |
Unrealized Loss | 0 | (1) |
Estimated Fair Value | 995 | 750 |
Classified as: | | |
Cash equivalents | 14 | 15 |
Total cash equivalents and marketable securities | 995 | 750 |
Debt securities issued by the United States Treasury | | |
Summary of cash equivalents and marketable securities: | | |
Available-for-sale Securities, Amortized Cost Basis | 554 | 534 |
Unrealized Gain | 1 | 3 |
Unrealized Loss | 0 | 0 |
Estimated Fair Value | 555 | 537 |
Classified as: | | |
Total cash equivalents and marketable securities | 555 | 537 |
Asset-backed Securities | | |
Summary of cash equivalents and marketable securities: | | |
Available-for-sale Securities, Amortized Cost Basis | 472 | 453 |
Unrealized Gain | 0 | 0 |
Unrealized Loss | 0 | 0 |
Estimated Fair Value | 472 | 453 |
Classified as: | | |
Cash equivalents | 1 | |
Total cash equivalents and marketable securities | 472 | 453 |
Mortgage backed securities issued by United Sates government-sponsored enterprises | | |
Summary of cash equivalents and marketable securities: | | |
Available-for-sale Securities, Amortized Cost Basis | 240 | 274 |
Unrealized Gain | 4 | 5 |
Unrealized Loss | (1) | (1) |
Estimated Fair Value | 243 | 278 |
Classified as: | | |
Total cash equivalents and marketable securities | 243 | 278 |
Unrealized Loss Position, Fair Value | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 73 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 26 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 99 | |
Unrealized Loss Position, Aggregate Losses | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (1) | |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (1) | |
Foreign government bonds | | |
Summary of cash equivalents and marketable securities: | | |
Available-for-sale Securities, Amortized Cost Basis | 83 | 85 |
Unrealized Gain | 0 | 0 |
Unrealized Loss | 0 | 0 |
Estimated Fair Value | 83 | 85 |
Classified as: | | |
Total cash equivalents and marketable securities | 83 | 85 |
Money market funds | | |
Summary of cash equivalents and marketable securities: | | |
Available-for-sale Securities, Amortized Cost Basis | 30 | 132 |
Unrealized Gain | 0 | 0 |
Unrealized Loss | 0 | 0 |
Estimated Fair Value | 30 | 132 |
Classified as: | | |
Total cash equivalents and marketable securities | $ 30 | $ 132 |