Fair Value Measurements Carrying Value and Fair Value (Details) - USD ($) $ in Millions	Jul. 29, 2017	Jan. 28, 2017
Senior Notes [Member] | January 2023 Notes [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 497	$ 497
Senior Notes [Member] | January 2023 Notes [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	506	509
Senior Notes [Member] | January 2018 Notes [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term Debt, Fair Value	500	499
Senior Notes [Member] | January 2018 Notes [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term Debt, Fair Value	$ 502	$ 503