Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Apr. 30, 2013
Taxes [Line Items]
Statutory federal income tax rate	35.00%
Gross unrecognized tax benefits	$ 105.5
Unrecognized tax benefits that would affect effective tax rate	92.0
Estimated potential decrease in underlying unrecognized tax benefits, minimum	0
Estimated potential decrease in underlying unrecognized tax benefits, maximum	$ 21

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The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems.

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- Definition

The estimated lower bound of the reasonably possible change in the total amount of the unrecognized tax benefit (that will significantly increase or decrease within twelve months of the balance sheet date) for a tax position taken.

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The estimated upper bound of the reasonably possible change in the total amount of the unrecognized tax benefit (that will significantly increase or decrease within twelve months of the balance sheet date) for a tax position taken.

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The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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