Retirement Benefit Plans (Investments at Fair Value) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Jan. 31, 2015
Feb. 01, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total investment assets at fair value $ 5,943 $ 5,344
Total investment liabilities at fair value (433)  
Accounts payable, net (36) (37)
Total net assets 5,474 5,140
Plan assets at fair value, description Cash – Cash is valued at cost which approximates fair value, and is classified as level 1 of the fair value hierarchy.   Common Collective Trusts – Common collective trusts are pools of investments within cash equivalents, equity and fixed income that are benchmarked relative to a comparable index. They are valued on the basis of the relative interest of each participating investor in the fair value of the underlying assets. The underlying assets are valued at net asset value (NAV) and are classified as level 2 of the fair value hierarchy.   Equity Securities – Equity securities are common stocks and preferred stocks valued based on the price of the security as listed on an open active exchange and classified as level 1 of the fair value hierarchy, as well as warrants and preferred stock that are valued at a price, which is based on a broker quote in an over-the-counter market, and are classified as level 2 of the fair value hierarchy.   Private Equity – Private equity is composed of interests in private equity funds valued on the basis of the relative interest of each participating investor in the fair value of the underlying assets and/or common stock of privately held companies. There are no observable market values for private equity funds. The valuations for the funds are derived using a combination of different methodologies including (1) the market approach, which consists of analyzing market transactions for comparable assets, (2) the income approach using the discounted cash flow model, or (3) cost method. Private equity funds also provide audited financial statements. Private equity investments are classified as level 3 of the fair value hierarchy. Corporate Bonds – Corporate bonds and Corporate loans are valued at a price which is based on observable market information in primary markets or a broker quote in an over-the-counter market, and are classified as level 2 or level 3 of the fair value hierarchy.    Swaps – swap contracts are based on broker quotes in an over-the-counter market and are classified as level 2 of the fair value hierarchy.   Government, Municipal Bonds and Mortgaged Backed Securities  – Government and municipal securities are valued at a price based on a broker quote in an over-the-counter market and classified as level 2 of the fair value hierarchy. Mortgage backed securities are valued at a price based on observable market information or a broker quote in an over-the-counter market and classified as level 2 of the fair value hierarchy.   Other fixed income – non-mortgage asset backed securities, collateral held in short-term investments for derivative contract and derivatives composed of futures contracts, option contracts and other fix income derivatives valued at a price based on observable market information or a broker quote in an over-the-counter market and classified as level 2 of the fair value hierarchy.       Real Estate – Real estate is comprised of public and private real estate investments. Real estate investments through registered investment companies that trade on an exchange are classified as level 1 of the fair value hierarchy. Investments through open end private real estate funds that are valued at the reported NAV are classified as level 2 of the fair value hierarchy. Private real estate investments through partnership interests that are valued based on different methodologies including discounted cash flow, direct capitalization and market comparable analysis are classified as level 3 of the fair value hierarchy. Hedge Fund – Hedge funds exposure is through fund of funds, which are made up of over 30 different hedge fund managers diversified over different hedge strategies. The fair value of the hedge fund is determined by the fund's administrator using valuation provided by the third party administrator for each of the underlying funds.  
Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1]  
Total investment assets at fair value 947 [1] 1,680 [1]
Total investment liabilities at fair value (2) [1] (2) [1]
Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Total investment assets at fair value 4,236 [1] 2,992 [1]
Total investment liabilities at fair value (431) [1] (239) [1]
Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0  
Total investment assets at fair value 760 672
Total investment liabilities at fair value 0 0
Cash and cash equivalents total [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 50 190
Cash and cash equivalents total [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 10 [1] 158 [1]
Cash and cash equivalents total [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 40 [1] 32 [1]
Cash and cash equivalents total [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Cash, benefit plan [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 12 158
Cash, benefit plan [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 10 [1] 158 [1]
Cash, benefit plan [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 2 [1] 0 [1]
Cash, benefit plan [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Common collective trusts [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 38 32
Common collective trusts [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value   0 [1]
Common collective trusts [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 38 [1] 32 [1]
Common collective trusts [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value   0
Equity securities total [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 1,537 2,266
Equity securities total [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 837 [1] 1,403 [1]
Equity securities total [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 419 [1] 565 [1]
Equity securities total [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 281 298
Equity securities held within common collective trusts, domestic [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 222 224
Equity securities held within common collective trusts, domestic [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Equity securities held within common collective trusts, domestic [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 222 [1] 224 [1]
Equity securities held within common collective trusts, domestic [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Equity securities held within common collective trusts, international [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 197 335
Equity securities held within common collective trusts, international [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Equity securities held within common collective trusts, international [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 197 [1] 335 [1]
Equity securities held within common collective trusts, international [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Equity securities, domestic [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 733 1,206
Equity securities, domestic [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 733 [1] 1,206 [1]
Equity securities, domestic [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Equity securities, domestic [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Equity securities, international [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 104 203
Equity securities, international [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 104 [1] 197 [1]
Equity securities, international [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 6 [1]
Equity securities, international [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Private equity [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 281 298
Private equity [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Private equity [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Private equity [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 281 298
Fixed income total [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 3,769 2,394
Investment liabilities at fair value (433) (241)
Total investment liabilities at fair value   (241)
Fixed income total [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 1 [1]
Investment liabilities at fair value (2) [1] (2) [1]
Fixed income total [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 3,757 [1] 2,376 [1]
Investment liabilities at fair value (431) [1] (239) [1]
Fixed income total [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 12 17
Investment liabilities at fair value 0 0
Debt securities held within common collective trusts [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 1,695 1,099
Debt securities held within common collective trusts [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Debt securities held within common collective trusts [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 1,695 [1] 1,099 [1]
Debt securities held within common collective trusts [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Corporate bonds [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 1,326 849
Corporate bonds [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Corporate bonds [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 1,319 [1] 838 [1]
Corporate bonds [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 7 11
Swaps [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 415 238
Investment liabilities at fair value (428) (237)
Swaps [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Investment liabilities at fair value 0 [1] 0 [1]
Swaps [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 415 [1] 238 [1]
Investment liabilities at fair value (428) [1] (237) [1]
Swaps [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Investment liabilities at fair value 0 0
Municipal bonds [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 66 50
Municipal bonds [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Municipal bonds [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 66 [1] 50 [1]
Municipal bonds [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Mortgage backed securities [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 5 6
Mortgage backed securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Mortgage backed securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 5 [1] 6 [1]
Mortgage backed securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Corporate loans [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 74 33
Corporate loans [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Corporate loans [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 69 [1] 27 [1]
Corporate loans [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 5 6
Government securities [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 167 106
Government securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Government securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 167 [1] 106 [1]
Government securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Other fixed income [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 21 13
Investment liabilities at fair value (5) (4)
Other fixed income [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 1 [1]
Investment liabilities at fair value (2) [1] (2) [1]
Other fixed income [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 21 [1] 12 [1]
Investment liabilities at fair value (3) [1] (2) [1]
Other fixed income [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Investment liabilities at fair value 0 0
Real estate total [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 273 341
Real estate total [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 100 [1] 118 [1]
Real estate total [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 20 [1] 19 [1]
Real estate total [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 153 204
Public REITs [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 100 118
Public REITs [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 100 [1] 118 [1]
Public REITs [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Public REITs [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 0
Private real estate [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 173 223
Private real estate [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1] 0 [1]
Private real estate [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 20 [1] 19 [1]
Private real estate [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 153 204
Other Investments [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 314  
Other Investments [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1]  
Other Investments [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1]  
Other Investments [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 314  
Hedge Funds [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 314  
Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1]  
Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value 0 [1]  
Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Investments at fair value $ 314  
[1] There were no significant transfers in or out of level 1 or 2 investments.