Schedule of Reconciliation of Provision for Income Taxes (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Income Tax Disclosure [Abstract]
Amount computed at the statutory federal income tax rate (35%)	$ 31	$ 122	$ (57)
State income taxes, net of federal tax benefit	0	10	(3)
Change in accruals for uncertain tax positions	(5)	(1)	(2)
CityTime uncertain tax liability	0	(96)	96
Research and development credits	(3)	(5)	(3)
Dividends paid to employee stock ownership plan	(22)	(9)	0
U.S. manufacturing activity benefit	(3)	(1)	(4)
Non-deductible penalties	4	0	46
Other	2	3	0
Total	$ 4	$ 23	$ 73
Effective income tax rate	4.50%	6.60%	(45.10%)