Stock-Based Compensation (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Jan. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Option, Outstanding at January 31, 2012	4,422,243
Options, Granted	281,828
Options, Exercised	(553,818)
Options, Forfeited/expired	(165,756)
Option, Outstanding at January 31, 2013	3,984,497
Options, exercisable (fully vested) at January 31, 2013	2,917,569
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted Average Exercise Price, Outstanding at January 31, 2012	$ 34.53
Weighted Average Exercise Price, Granted	$ 14.74
Weighted Average Exercise Price, Exercised	$ 15.11
Weighted Average Exercise Price, Forfeited/expired	$ 39.50
Weighted Average Exercise Price, Outstanding at January 31, 2013	$ 35.62
Weighted Average Exercise Price, Exercisable as of January 31, 2013	$ 42.95
Weighted Average Remaining Contractual Term, Outstanding at January 31, 2013	4 years 10 months 24 days
Weighted Average Remaining Contractual Term, Exercisable	3 years 9 months 4 days
Intrinsic Value, Outstanding at January 31, 2013	$ 3,313
Intrinsic Value, Exercisable at January 31, 2013	$ 1,556

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Number of share options (or share units) exercised during the current period.

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