Stock-Based Compensation (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
Jul. 31, 2012	Jan. 31, 2012
Stock-Based Compensation (Textual) [Abstract]
Stock options outstanding	8,665,563	8,582,511
Aggregate intrinsic value of options outstanding	$ 6.9
Stock Based Compensation (Additional Textual) [Abstract]
Number of options vested and expected to vest	5,347,619
Weighted average exercise price of vested shares	$ 2.78
Aggregate intrinsic value of options exercisable	4.7
Unrecognized compensation costs	4.1
Expected dividend yield	0.00%
Maximum [Member]
Stock-Based Compensation (Textual) [Abstract]
Unrecognized compensation costs recognition period	3 years 6 months
Minimum [Member]
Stock-Based Compensation (Textual) [Abstract]
Unrecognized compensation costs recognition period	3 years
Restricted stock units (RSUs) [Member]
Stock-Based Compensation (Textual) [Abstract]
Stock options outstanding	0
Aggregate intrinsic value of options outstanding	$ 5.2
Restricted stock units (RSUs) [Member] \| Maximum [Member]
Stock-Based Compensation (Textual) [Abstract]
Unrecognized compensation costs recognition period	4 years
Restricted stock units (RSUs) [Member] \| Minimum [Member]
Stock-Based Compensation (Textual) [Abstract]
Unrecognized compensation costs recognition period	3 years

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

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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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of fully vested and expected to vest options that are exercisable.

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The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date.

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- Definition

As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise prices of fully vested and expected to vest options outstanding.

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