Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 25, 2015	Oct. 26, 2014	Oct. 25, 2015	Oct. 26, 2014
Income Taxes
Income tax expense (benefit)	$ (1)	$ 36	$ 83	$ 90
Effective Income Tax Rate, Continuing Operations	(0.50%)	17.30%	16.90%	17.00%
Tax reserve release related to Icera			$ 49
Icera deferred tax asset write-off			$ 27
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate			35.00%