Schedule of Reconciliation of Provision for Income Taxes (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Income Taxes [Abstract]
Amount computed at the statutory federal income tax rate (35%)	$ 230	$ 68	$ 299
State income taxes, net of federal tax benefit	22	8	28
Change in accruals for uncertain tax positions		1	(7)
CityTime uncertain tax liability	(96)	96
Research and development credits	(10)	(7)	(8)
Dividends paid to employee stock ownership plan	(9)
U.S. manufacturing activity benefit	(2)	(5)	(5)
Non-deductible penalties		49
Total	$ 135	$ 210	$ 307
Effective income tax rate	20.50%	107.70%	35.90%

Income tax reconciliation non-deductible penalties

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Income Tax Reconciliation Tax Credits Manufacturing Activity Benefit

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A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to pretax Income or Loss from continuing operations; income tax expense or benefit may include interest and penalties on tax uncertainties based on the entity's accounting policy.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to the deduction for dividends paid to employee stock ownership plans received under enacted tax laws.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to state and local income tax expense or benefit.

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