Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Apr. 30, 2013	Apr. 30, 2012	Jan. 31, 2013
Disclosure Income Taxes Additional Information [Abstract]
Effective tax rate	381.00%	3.00%
Period specific items benefit	$ 360
Effective income tax rate forecast	13.00%
U.S. federal statutory rate	35.00%
Income taxes associated with uncertain income tax positions	28,305
Liability for uncertain tax positions, current	5,535
Income tax liability	$ 22,770		$ 22,663

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

+ References

No definition available.

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- Definition

-- The net amount of all increases and decreases in the period of discrete tax items --

+ References

No definition available.

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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.

+ References

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- Definition

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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The current portion of the amount recognized for uncertain tax positions as of the balance sheet date.

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The noncurrent portion of the amount recognized for uncertain tax positions as of the balance sheet date.

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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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