Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010	Jan. 31, 2011
Income Taxes [Line Items]
Effective tax rate			20.00%
Effective Tax Rate	(6.00%)	5.00%	(20.00%)	(12.00%)
Period specific items benefit	$ (3,719)	$ (359)	$ (8,770)	$ (2,281)
Forecasted tax rate			2.00%
U.S. federal statutory rate			35.00%
Income taxes associated with uncertain income tax positions	$ 34,432		$ 34,432		$ 44,095

Carrying amount as of the balance sheet date of the unpaid sum of the known and estimated amounts payable to satisfy all domestic and foreign income tax obligations due beyond one year or the operating cycle, whichever is longer. Alternate captions include income taxes payable, noncurrent.

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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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- 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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