Schedule of Selected Quarterly Financial Data (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			4 Months Ended	6 Months Ended	12 Months Ended
	Jan. 31, 2014	Nov. 01, 2013	Aug. 02, 2013	Jan. 31, 2014	Aug. 02, 2013	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Intangible asset impairment charges		$ 19	$ 30			$ 51	$ 0	$ 0
Bad debt expense		42				44	2	0
Separation transaction expenses, net of tax	$ 7	$ 25			$ 33	$ 40	$ 7
Reverse stock split				0.25