Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Millions		May. 01, 2016	Jan. 31, 2016
Financial assets and liabilities measured at fair value:
Cash equivalents		$ 34	$ 232
Level 2
Financial assets and liabilities measured at fair value:
Convertible Debt, Fair Value Disclosures	[1]	2,675	2,273
Fair value of interest rate swap liability	[2]	(8)	(7)
Corporate debt securities
Financial assets and liabilities measured at fair value:
Cash equivalents		3	51
Marketable securities		1,790	1,850
Corporate debt securities | Level 2
Financial assets and liabilities measured at fair value:
Assets, Fair Value Disclosure, Recurring	[3]	1,793	1,901
Debt securities of United States government agencies | Level 2
Financial assets and liabilities measured at fair value:
Assets, Fair Value Disclosure, Recurring	[4]	1,028	1,170
Debt securities issued by the United States Treasury | Level 2
Financial assets and liabilities measured at fair value:
Assets, Fair Value Disclosure, Recurring	[4]	718	801
Asset-backed Securities | Level 2
Financial assets and liabilities measured at fair value:
Assets, Fair Value Disclosure, Recurring	[4]	381	435
Mortgage backed securities issued by United Sates government-sponsored enterprises | Level 2
Financial assets and liabilities measured at fair value:
Assets, Fair Value Disclosure, Recurring	[4]	188	231
Foreign government bonds | Level 2
Financial assets and liabilities measured at fair value:
Assets, Fair Value Disclosure, Recurring	[4]	102	92
Money market funds | Level 1
Financial assets and liabilities measured at fair value:
Assets, Fair Value Disclosure, Recurring	[5]	$ 31	$ 43

[1] The Notes are carried on our Condensed Consolidated Balance Sheets at their original issuance value, net of unamortized debt discount, and are not marked to fair value each period. See Note 11 of these Notes to Condensed Consolidated Financial Statements for additional information on the Notes.

[2] Please refer to Note 9 of these Notes to Condensed Consolidated Financial Statements for a discussion regarding our interest rate swap.

[3] Included $3 million and $51 million in cash equivalents as of May 1, 2016 and January 31, 2016, respectively, and $1.79 billion and $1.85 billion in marketable securities as of May 1, 2016 and January 31, 2016, respectively, on the Condensed Consolidated Balance Sheets.

[4] Reported in marketable securities on the Condensed Consolidated Balance Sheets.

[5] Reported in cash equivalents on the Condensed Consolidated Balance Sheets.